Finish converting most of the undeprecated api to jspecify

patches/api/Add-EntityDyeEvent-and-CollarColorable-interface.patch

@@ -14,11 +14,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import org.bukkit.DyeColor;
 +import org.bukkit.entity.LivingEntity;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Entities that can have their collars colored.
 + */
++@NullMarked
 +public interface CollarColorable extends LivingEntity {
 +
 +    /**
@@ -26,14 +27,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the color of the collar
 +     */
-+    @NotNull DyeColor getCollarColor();
++    DyeColor getCollarColor();
 +
 +    /**
 +     * Set the collar color of this entity
 +     *
 +     * @param color the color to apply
 +     */
-+    void setCollarColor(@NotNull DyeColor color);
++    void setCollarColor(DyeColor color);
 +}
 diff --git a/src/main/java/io/papermc/paper/event/entity/EntityDyeEvent.java b/src/main/java/io/papermc/paper/event/entity/EntityDyeEvent.java
 new file mode 100644

patches/api/Add-FeatureFlag-API.patch

@@ -14,9 +14,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import java.util.Set;
 +import org.bukkit.FeatureFlag;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Implemented by types in built-in registries that are controlled by {@link FeatureFlag FeatureFlags}.
@@ -24,6 +24,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @apiNote When a type that currently implements this interface transitions to being data-drive, this
 + * interface will be removed from that type in the following major version.
 + */
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface FeatureDependant {
 +
@@ -33,7 +34,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the immutable set of feature flags
 +     */
-+    default @Unmodifiable @NonNull Set<FeatureFlag> requiredFeatures() {
++    default @Unmodifiable Set<FeatureFlag> requiredFeatures() {
 +        return FeatureFlagProvider.provider().requiredFeatures(this);
 +    }
 +}
@@ -50,7 +51,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Set;
 +import org.bukkit.FeatureFlag;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
++@NullMarked
 +@ApiStatus.Internal
 +interface FeatureFlagProvider {
 +
@@ -72,14 +75,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import java.util.Set;
 +import org.bukkit.FeatureFlag;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Implemented by types that hold {@link FeatureFlag FeatureFlags} like
 + * {@link org.bukkit.generator.WorldInfo} and {@link org.bukkit.RegionAccessor}.
 + */
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface FeatureFlagSetHolder {
 +
@@ -88,7 +92,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return true if enabled
 +     */
-+    default boolean isEnabled(final @NonNull FeatureDependant featureDependant) {
++    default boolean isEnabled(final FeatureDependant featureDependant) {
 +        return this.getFeatureFlags().containsAll(featureDependant.requiredFeatures());
 +    }
 +
@@ -97,7 +101,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return all enabled {@link FeatureFlag FeatureFlags}
 +     */
-+    @Unmodifiable @NonNull Set<FeatureFlag> getFeatureFlags();
++    @Unmodifiable Set<FeatureFlag> getFeatureFlags();
 +}
 diff --git a/src/main/java/org/bukkit/FeatureFlag.java b/src/main/java/org/bukkit/FeatureFlag.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
@@ -189,12 +193,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import java.util.HashSet;
 +import java.util.Set;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.framework.qual.DefaultQualifier;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
-+@DefaultQualifier(NonNull.class)
++@NullMarked
 +record FeatureFlagImpl(NamespacedKey key) implements FeatureFlag {
 +
 +    static final Set<FeatureFlag> ALL_FLAGS = new HashSet<>();
@@ -205,7 +208,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    @ApiStatus.Internal
-+    @DefaultQualifier(NonNull.class)
 +    record Deprecated(NamespacedKey key) implements FeatureFlag {
 +
 +        @Override

patches/api/Add-FluidState-API.patch

@@ -15,13 +15,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.Fluid;
 +import org.bukkit.Location;
 +import org.bukkit.util.Vector;
-+import org.jetbrains.annotations.NotNull;
 +import org.jetbrains.annotations.Range;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A representation of a fluid in a specific state of data.
 + * This type is not linked to a specific location and hence mostly resembles a {@link org.bukkit.block.data.BlockData}.
 + */
++@NullMarked
 +public interface FluidData extends Cloneable {
 +
 +    /**
@@ -29,14 +30,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the fluid type
 +     */
-+    @NotNull Fluid getFluidType();
++    Fluid getFluidType();
 +
 +    /**
 +     * Returns a copy of this FluidData.
 +     *
 +     * @return a copy of the fluid data
 +     */
-+    @NotNull FluidData clone();
++    FluidData clone();
 +
 +    /**
 +     * Computes the direction of the flow of the liquid at the given location as a vector.
@@ -48,7 +49,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param location - the location to check the liquid flow
 +     * @return the flow direction vector at the given location
 +     */
-+    @NotNull Vector computeFlowDirection(@NotNull Location location);
++    Vector computeFlowDirection(Location location);
 +
 +    /**
 +     * Returns the level of liquid this fluid data holds.
@@ -69,7 +70,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the height as a float value
 +     */
 +    @Range(from = 0, to = 1)
-+    float computeHeight(@NotNull Location location);
++    float computeHeight(Location location);
 +
 +    /**
 +     * Returns whether this fluid is a source block

patches/api/Add-Lifecycle-Event-system.patch

@@ -17,13 +17,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEventManager;
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEventOwner;
  import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
+ import org.jspecify.annotations.NullMarked;
  
- /**
+@@ -0,0 +0,0 @@ import org.jspecify.annotations.NullMarked;
-  * Represents the context provided to a {@link PluginBootstrap} during both the bootstrapping and plugin
-@@ -0,0 +0,0 @@ import org.jetbrains.annotations.ApiStatus;
-  */
  @ApiStatus.Experimental
+ @NullMarked
  @ApiStatus.NonExtendable
 -public interface BootstrapContext extends PluginProviderContext {
 +public interface BootstrapContext extends PluginProviderContext, LifecycleEventOwner {
@@ -34,7 +32,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the lifecycle event manager
 +     */
-+    @NotNull LifecycleEventManager<BootstrapContext> getLifecycleManager();
++    LifecycleEventManager<BootstrapContext> getLifecycleManager();
  }
 diff --git a/src/main/java/io/papermc/paper/plugin/lifecycle/event/LifecycleEvent.java b/src/main/java/io/papermc/paper/plugin/lifecycle/event/LifecycleEvent.java
 new file mode 100644
@@ -71,7 +69,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.handler.configuration.LifecycleEventHandlerConfiguration;
 +import io.papermc.paper.plugin.lifecycle.event.types.LifecycleEventType;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Manages a plugin's lifecycle events. Can be obtained
@@ -80,6 +78,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <O> the owning type, {@link org.bukkit.plugin.Plugin} or {@link io.papermc.paper.plugin.bootstrap.BootstrapContext}
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface LifecycleEventManager<O extends LifecycleEventOwner> {
 +
@@ -102,7 +101,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param eventHandler the handler for that event
 +     * @param <E> the type of the event object
 +     */
-+    default <E extends LifecycleEvent> void registerEventHandler(final @NotNull LifecycleEventType<? super O, ? extends E, ?> eventType, final @NotNull LifecycleEventHandler<? super E> eventHandler) {
++    default <E extends LifecycleEvent> void registerEventHandler(final LifecycleEventType<? super O, ? extends E, ?> eventType, final LifecycleEventHandler<? super E> eventHandler) {
 +        this.registerEventHandler(eventType.newHandler(eventHandler));
 +    }
 +
@@ -115,7 +114,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param handlerConfiguration the handler configuration to register
 +     */
-+    void registerEventHandler(@NotNull LifecycleEventHandlerConfiguration<? super O> handlerConfiguration);
++    void registerEventHandler(LifecycleEventHandlerConfiguration<? super O> handlerConfiguration);
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/lifecycle/event/LifecycleEventOwner.java b/src/main/java/io/papermc/paper/plugin/lifecycle/event/LifecycleEventOwner.java
 new file mode 100644
@@ -127,7 +126,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import io.papermc.paper.plugin.configuration.PluginMeta;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Implemented by types that are considered owners
@@ -137,6 +136,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * event handlers.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface LifecycleEventOwner {
 +
@@ -145,7 +145,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the plugin meta
 +     */
-+    @NotNull PluginMeta getPluginMeta();
++    PluginMeta getPluginMeta();
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/lifecycle/event/handler/LifecycleEventHandler.java b/src/main/java/io/papermc/paper/plugin/lifecycle/event/handler/LifecycleEventHandler.java
 new file mode 100644
@@ -157,7 +157,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEvent;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A handler for a specific event. Can be implemented
@@ -166,10 +166,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <E> the event
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@FunctionalInterface
 +public interface LifecycleEventHandler<E extends LifecycleEvent> {
 +
-+    void run(@NotNull E event);
++    void run(E event);
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/lifecycle/event/handler/configuration/LifecycleEventHandlerConfiguration.java b/src/main/java/io/papermc/paper/plugin/lifecycle/event/handler/configuration/LifecycleEventHandlerConfiguration.java
 new file mode 100644
@@ -182,6 +183,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEventOwner;
 +import io.papermc.paper.plugin.lifecycle.event.handler.LifecycleEventHandler;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Base type for constructing configured event handlers for
@@ -192,6 +194,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + */
 +@SuppressWarnings("unused")
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface LifecycleEventHandlerConfiguration<O extends LifecycleEventOwner> {
 +}
@@ -206,6 +209,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEventOwner;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Handler configuration for event types that allow "monitor" handlers.
@@ -213,6 +217,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <O> the required owner type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface MonitorLifecycleEventHandlerConfiguration<O extends LifecycleEventOwner> extends LifecycleEventHandlerConfiguration<O> {
 +
@@ -237,6 +242,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEventOwner;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Handler configuration that allows both "monitor" and prioritized handlers.
@@ -245,6 +251,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <O> the required owner type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface PrioritizedLifecycleEventHandlerConfiguration<O extends LifecycleEventOwner> extends LifecycleEventHandlerConfiguration<O> {
 +
@@ -300,7 +307,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEvent;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A lifecycle event that exposes a {@link Registrar} of some kind
@@ -311,6 +318,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see ReloadableRegistrarEvent
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface RegistrarEvent<R extends Registrar> extends LifecycleEvent {
 +
@@ -320,7 +328,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the registrar
 +     */
 +    @Contract(pure = true)
-+    @NotNull R registrar();
++    R registrar();
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/lifecycle/event/registrar/ReloadableRegistrarEvent.java b/src/main/java/io/papermc/paper/plugin/lifecycle/event/registrar/ReloadableRegistrarEvent.java
 new file mode 100644
@@ -332,7 +340,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A lifecycle event that exposes a {@link Registrar} that is
@@ -342,6 +350,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see RegistrarEvent
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface ReloadableRegistrarEvent<R extends Registrar> extends RegistrarEvent<R> {
 +
@@ -351,7 +360,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the cause
 +     */
 +    @Contract(pure = true)
-+    @NotNull Cause cause();
++    Cause cause();
 +
 +    @ApiStatus.Experimental
 +    enum Cause {
@@ -383,7 +392,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.handler.configuration.PrioritizedLifecycleEventHandlerConfiguration;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Base type for all types of lifecycle events. Differs from
@@ -397,6 +406,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <C> the configuration type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface LifecycleEventType<O extends LifecycleEventOwner, E extends LifecycleEvent, C extends LifecycleEventHandlerConfiguration<O>> {
 +
@@ -406,7 +416,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the name
 +     */
 +    @Contract(pure = true)
-+    @NotNull String name();
++    String name();
 +
 +    /**
 +     * Create a configuration for this event with the specified
@@ -417,7 +427,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see LifecycleEventManager#registerEventHandler(LifecycleEventHandlerConfiguration)
 +     */
 +    @Contract("_ -> new")
-+    @NotNull C newHandler(@NotNull LifecycleEventHandler<? super E> handler);
++    C newHandler(LifecycleEventHandler<? super E> handler);
 +
 +    /**
 +     * Lifecycle event type that supports separate registration
@@ -458,8 +468,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Optional;
 +import java.util.ServiceLoader;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
++@NullMarked
 +interface LifecycleEventTypeProvider {
 +
 +    Optional<LifecycleEventTypeProvider> INSTANCE = ServiceLoader.load(LifecycleEventTypeProvider.class)
@@ -487,6 +499,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEventOwner;
 +import org.bukkit.plugin.Plugin;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Holds various types of lifecycle events for
@@ -494,6 +507,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * in {@link LifecycleEventManager}.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public final class LifecycleEvents {
 +
 +    //<editor-fold desc="helper methods" defaultstate="collapsed">

patches/api/Add-Moving-Piston-API.patch

@@ -15,8 +15,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.block.BlockFace;
 +import org.bukkit.block.TileState;
 +import org.bukkit.block.data.BlockData;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
++@NullMarked
 +public interface MovingPiston extends TileState {
 +
 +    /**
@@ -24,7 +25,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the pushed block
 +     */
-+    @NotNull
 +    BlockData getMovingBlock();
 +
 +    /**
@@ -33,7 +33,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the direction
 +     */
-+    @NotNull
 +    BlockFace getDirection();
 +
 +    /**

patches/api/Add-Position.patch

@@ -16,15 +16,17 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.block.BlockFace;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A position represented with integers.
 + * <p>
 + * <b>May see breaking changes until Experimental annotation is removed.</b>
++ *
 + * @see FinePosition
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public interface BlockPosition extends Position {
 +
 +    @Override
@@ -53,17 +55,17 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    @Override
-+    default @NotNull BlockPosition toBlock() {
++    default BlockPosition toBlock() {
 +        return this;
 +    }
 +
 +    @Override
-+    default @NotNull BlockPosition offset(int x, int y, int z) {
++    default BlockPosition offset(final int x, final int y, final int z) {
 +        return x == 0 && y == 0 && z == 0 ? this : new BlockPositionImpl(this.blockX() + x, this.blockY() + y, this.blockZ() + z);
 +    }
 +
 +    @Override
-+    default @NotNull FinePosition offset(double x, double y, double z) {
++    default FinePosition offset(final double x, final double y, final double z) {
 +        return new FinePositionImpl(this.blockX() + x, this.blockY() + y, this.blockZ() + z);
 +    }
 +
@@ -74,7 +76,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the offset block position
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    default @NotNull BlockPosition offset(@NotNull BlockFace blockFace) {
++    default BlockPosition offset(final BlockFace blockFace) {
 +        return this.offset(blockFace, 1);
 +    }
 +
@@ -87,7 +89,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the offset block position
 +     */
 +    @Contract(pure = true)
-+    default @NotNull BlockPosition offset(@NotNull BlockFace blockFace, int amount) {
++    default BlockPosition offset(final BlockFace blockFace, final int amount) {
 +        return amount == 0 ? this : new BlockPositionImpl(this.blockX() + (blockFace.getModX() * amount), this.blockY() + (blockFace.getModY() * amount), this.blockZ() + (blockFace.getModZ() * amount));
 +    }
 +
@@ -100,7 +102,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the offset block position
 +     */
 +    @Contract(pure = true)
-+    default @NotNull BlockPosition offset(@NotNull Axis axis, int amount) {
++    default BlockPosition offset(final Axis axis, final int amount) {
 +        return amount == 0 ? this : switch (axis) {
 +            case X -> new BlockPositionImpl(this.blockX() + amount, this.blockY(), this.blockZ());
 +            case Y -> new BlockPositionImpl(this.blockX(), this.blockY() + amount, this.blockZ());
@@ -127,17 +129,18 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.math;
 +
 +import org.bukkit.util.NumberConversions;
-+import org.bukkit.util.Vector;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A position represented with doubles.
 + * <p>
 + * <b>May see breaking changes until Experimental annotation is removed.</b>
++ *
 + * @see BlockPosition
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public interface FinePosition extends Position {
 +
 +    @Override
@@ -166,17 +169,17 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    @Override
-+    default @NotNull BlockPosition toBlock() {
++    default BlockPosition toBlock() {
 +        return new BlockPositionImpl(this.blockX(), this.blockY(), this.blockZ());
 +    }
 +
 +    @Override
-+    default @NotNull FinePosition offset(int x, int y, int z) {
++    default FinePosition offset(final int x, final int y, final int z) {
 +        return this.offset((double) x, y, z);
 +    }
 +
 +    @Override
-+    default @NotNull FinePosition offset(double x, double y, double z) {
++    default FinePosition offset(final double x, final double y, final double z) {
 +        return x == 0.0 && y == 0.0 && z == 0.0 ? this : new FinePositionImpl(this.x() + x, this.y() + y, this.z() + z);
 +    }
 +}
@@ -203,7 +206,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.util.Vector;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Common interface for {@link FinePosition} and {@link BlockPosition}.
@@ -211,6 +214,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * <b>May see breaking changes until Experimental annotation is removed.</b>
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public interface Position {
 +
 +    FinePosition FINE_ZERO = new FinePositionImpl(0, 0, 0);
@@ -287,7 +291,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param z z value to offset
 +     * @return the offset position
 +     */
-+    @NotNull Position offset(int x, int y, int z);
++    Position offset(int x, int y, int z);
 +
 +    /**
 +     * Returns a position offset by the specified amounts.
@@ -297,7 +301,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param z z value to offset
 +     * @return the offset position
 +     */
-+    @NotNull FinePosition offset(double x, double y, double z);
++    FinePosition offset(double x, double y, double z);
 +
 +    /**
 +     * Returns a new position at the center of the block position this represents
@@ -305,7 +309,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new center position
 +     */
 +    @Contract(value = "-> new", pure = true)
-+    default @NotNull FinePosition toCenter() {
++    default FinePosition toCenter() {
 +        return new FinePositionImpl(this.blockX() + 0.5, this.blockY() + 0.5, this.blockZ() + 0.5);
 +    }
 +
@@ -316,7 +320,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the block position
 +     */
 +    @Contract(pure = true)
-+    @NotNull BlockPosition toBlock();
++    BlockPosition toBlock();
 +
 +    /**
 +     * Converts this position to a vector
@@ -324,7 +328,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new vector
 +     */
 +    @Contract(value = "-> new", pure = true)
-+    default @NotNull Vector toVector() {
++    default Vector toVector() {
 +        return new Vector(this.x(), this.y(), this.z());
 +    }
 +
@@ -335,7 +339,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new location
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    default @NotNull Location toLocation(@NotNull World world) {
++    default Location toLocation(final World world) {
 +        return new Location(world, this.x(), this.y(), this.z());
 +    }
 +
@@ -348,7 +352,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a position with those coords
 +     */
 +    @Contract(value = "_, _, _ -> new", pure = true)
-+    static @NotNull BlockPosition block(int x, int y, int z) {
++    static BlockPosition block(final int x, final int y, final int z) {
 +        return new BlockPositionImpl(x, y, z);
 +    }
 +
@@ -359,7 +363,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new position at that location
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    static @NotNull BlockPosition block(@NotNull Location location) {
++    static BlockPosition block(final Location location) {
 +        return new BlockPositionImpl(location.getBlockX(), location.getBlockY(), location.getBlockZ());
 +    }
 +
@@ -372,7 +376,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a position with those coords
 +     */
 +    @Contract(value = "_, _, _ -> new", pure = true)
-+    static @NotNull FinePosition fine(double x, double y, double z) {
++    static FinePosition fine(final double x, final double y, final double z) {
 +        return new FinePositionImpl(x, y, z);
 +    }
 +
@@ -383,7 +387,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new position at that location
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    static @NotNull FinePosition fine(@NotNull Location location) {
++    static FinePosition fine(final Location location) {
 +        return new FinePositionImpl(location.getX(), location.getY(), location.getZ());
 +    }
 +}

patches/api/Add-RegistryAccess-for-managing-registries.patch

@@ -105,14 +105,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.Keyed;
 +import org.bukkit.Registry;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Used for accessing different {@link Registry} instances
 + * by a {@link RegistryKey}. Get the main instance of {@link RegistryAccess}
 + * with {@link RegistryAccess#registryAccess()}.
 + */
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface RegistryAccess {
 +
@@ -121,7 +122,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the RegistryAccess instance
 +     */
-+    static @NotNull RegistryAccess registryAccess() {
++    static RegistryAccess registryAccess() {
 +        return RegistryAccessHolder.INSTANCE.orElseThrow(() -> new IllegalStateException("No RegistryAccess implementation found"));
 +    }
 +
@@ -134,7 +135,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @deprecated use {@link #getRegistry(RegistryKey)} with keys from {@link RegistryKey}
 +     */
 +    @Deprecated(since = "1.20.6", forRemoval = true)
-+    <T extends Keyed> @Nullable Registry<T> getRegistry(@NotNull Class<T> type);
++    <T extends Keyed> @Nullable Registry<T> getRegistry(Class<T> type);
 +
 +    /**
 +     * Gets the registry with the specified key.
@@ -147,7 +148,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    // Future note: We should have no trouble removing this generic qualifier when
 +    // registry types no longer have to be "keyed" as it shouldn't break ABI or API.
-+    <T extends Keyed> @NotNull Registry<T> getRegistry(@NotNull RegistryKey<T> registryKey);
++    <T extends Keyed> Registry<T> getRegistry(RegistryKey<T> registryKey);
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/RegistryAccessHolder.java b/src/main/java/io/papermc/paper/registry/RegistryAccessHolder.java
 new file mode 100644
@@ -171,13 +172,13 @@ diff --git a/src/main/java/io/papermc/paper/registry/RegistryKeyImpl.java b/src/
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/io/papermc/paper/registry/RegistryKeyImpl.java
 +++ b/src/main/java/io/papermc/paper/registry/RegistryKeyImpl.java
-@@ -0,0 +0,0 @@ record RegistryKeyImpl<T>(@NotNull Key key) implements RegistryKey<T> {
+@@ -0,0 +0,0 @@ record RegistryKeyImpl<T>(Key key) implements RegistryKey<T> {
  
      static final Set<RegistryKey<?>> REGISTRY_KEYS = Sets.newIdentityHashSet();
  
 +    // override equals and hashCode to this can be used to simulate an "identity" hashmap
 +    @Override
-+    public boolean equals(final Object obj) {
++    public boolean equals(final @Nullable Object obj) {
 +        return obj == this;
 +    }
 +

patches/api/Add-Shearable-API.patch

@@ -14,11 +14,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import net.kyori.adventure.sound.Sound;
 +import org.bukkit.entity.Entity;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents an entity that can be sheared.
 + */
++@NullMarked
 +public interface Shearable extends Entity {
 +
 +    /**
@@ -44,7 +45,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param source Sound source to play any sound effects on
 +     */
-+    void shear(@NotNull Sound.Source source);
++    void shear(Sound.Source source);
 +
 +    /**
 +     * Gets if the entity would be able to be sheared or not naturally using shears.

patches/api/Add-Tick-TemporalUnit.patch

@@ -12,40 +12,44 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.util;
 +
-+import net.kyori.adventure.util.Ticks;
-+import org.jetbrains.annotations.NotNull;
-+
 +import java.time.Duration;
 +import java.time.temporal.ChronoUnit;
 +import java.time.temporal.Temporal;
 +import java.time.temporal.TemporalUnit;
 +import java.util.Objects;
++import net.kyori.adventure.util.Ticks;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A TemporalUnit that represents the target length of one server tick. This is defined
 + * as 50 milliseconds. Note that this class is not for measuring the length that a tick
 + * took, rather it is used for simple conversion between times and ticks.
++ *
 + * @see #tick()
 + */
++@NullMarked
 +public final class Tick implements TemporalUnit {
++
 +    private static final Tick INSTANCE = new Tick(Ticks.SINGLE_TICK_DURATION_MS);
 +
 +    private final long milliseconds;
 +
 +    /**
 +     * Gets the instance of the tick temporal unit.
++     *
 +     * @return the tick instance
 +     */
-+    public static @NotNull Tick tick() {
++    public static Tick tick() {
 +        return INSTANCE;
 +    }
 +
 +    /**
 +     * Creates a new tick.
++     *
 +     * @param length the length of the tick in milliseconds
 +     * @see #tick()
 +     */
-+    private Tick(long length) {
++    private Tick(final long length) {
 +        this.milliseconds = length;
 +    }
 +
@@ -53,27 +57,29 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * Creates a duration from an amount of ticks. This is shorthand for
 +     * {@link Duration#of(long, TemporalUnit)} called with the amount of ticks and
 +     * {@link #tick()}.
++     *
 +     * @param ticks the amount of ticks
 +     * @return the duration
 +     */
-+    public static @NotNull Duration of(long ticks) {
++    public static Duration of(final long ticks) {
 +        return Duration.of(ticks, INSTANCE);
 +    }
 +
 +    /**
 +     * Gets the number of whole ticks that occur in the provided duration. Note that this
 +     * method returns an {@code int} as this is the unit that Minecraft stores ticks in.
++     *
 +     * @param duration the duration
 +     * @return the number of whole ticks in this duration
 +     * @throws ArithmeticException if the duration is zero or an overflow occurs
 +     */
-+    public int fromDuration(@NotNull Duration duration) {
++    public int fromDuration(final Duration duration) {
 +        Objects.requireNonNull(duration, "duration cannot be null");
 +        return Math.toIntExact(Math.floorDiv(duration.toMillis(), this.milliseconds));
 +    }
 +
 +    @Override
-+    public @NotNull Duration getDuration() {
++    public Duration getDuration() {
 +        return Duration.ofMillis(this.milliseconds);
 +    }
 +
@@ -96,12 +102,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +    @SuppressWarnings("unchecked") // following ChronoUnit#addTo
 +    @Override
-+    public <R extends Temporal> @NotNull R addTo(@NotNull R temporal, long amount) {
++    public <R extends Temporal> R addTo(final R temporal, final long amount) {
-+        return (R) temporal.plus(getDuration().multipliedBy(amount));
++        return (R) temporal.plus(this.getDuration().multipliedBy(amount));
 +    }
 +
 +    @Override
-+    public long between(@NotNull Temporal start, @NotNull Temporal end) {
++    public long between(final Temporal start, final Temporal end) {
 +        return start.until(end, ChronoUnit.MILLIS) / this.milliseconds;
 +    }
 +}

patches/api/Add-UnknownCommandEvent.patch

@@ -19,22 +19,23 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.event.HandlerList;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Thrown when a player executes a command that is not defined
 + */
++@NullMarked
 +public class UnknownCommandEvent extends Event {
 +
 +    private static final HandlerList HANDLER_LIST = new HandlerList();
 +
-+    @NotNull private final CommandSender sender;
++    private final CommandSender sender;
-+    @NotNull private final String commandLine;
++    private final String commandLine;
-+    @Nullable private Component message;
++    private @Nullable Component message;
 +
 +    @ApiStatus.Internal
-+    public UnknownCommandEvent(@NotNull final CommandSender sender, @NotNull final String commandLine, @Nullable final Component message) {
++    public UnknownCommandEvent(final CommandSender sender, final String commandLine, final @Nullable Component message) {
 +        super(false);
 +        this.sender = sender;
 +        this.commandLine = commandLine;
@@ -46,7 +47,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return Sender of the command
 +     */
-+    @NotNull
 +    public CommandSender getSender() {
 +        return this.sender;
 +    }
@@ -56,7 +56,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return Command sent
 +     */
-+    @NotNull
 +    public String getCommandLine() {
 +        return this.commandLine;
 +    }
@@ -67,9 +66,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return Unknown command message
 +     * @deprecated use {@link #message()}
 +     */
-+    @Nullable
 +    @Deprecated
-+    public String getMessage() {
++    public @Nullable String getMessage() {
 +        return this.message == null ? null : LegacyComponentSerializer.legacySection().serialize(this.message);
 +    }
 +
@@ -91,9 +89,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return Unknown command message
 +     */
-+    @Nullable
 +    @Contract(pure = true)
-+    public Component message() {
++    public @Nullable Component message() {
 +        return this.message;
 +    }
 +
@@ -108,13 +105,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        this.message = message;
 +    }
 +
-+    @NotNull
 +    @Override
 +    public HandlerList getHandlers() {
 +        return HANDLER_LIST;
 +    }
 +
-+    @NotNull
 +    public static HandlerList getHandlerList() {
 +        return HANDLER_LIST;
 +    }

patches/api/Add-basic-Datapack-API.patch

@@ -16,14 +16,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Set;
 +import net.kyori.adventure.text.Component;
 +import org.bukkit.FeatureFlag;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.Contract;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * This is a snapshot of a datapack on the server. It
 + * won't be updated as datapacks are updated.
 + */
++@NullMarked
 +public interface Datapack {
 +
 +    /**
@@ -32,21 +33,21 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the name of the pack
 +     */
 +    @Contract(pure = true)
-+    @NonNull String getName();
++    String getName();
 +
 +    /**
 +     * Gets the title component of this datapack.
 +     *
 +     * @return the title
 +     */
-+    @NonNull Component getTitle();
++    Component getTitle();
 +
 +    /**
 +     * Gets the description component of this datapack.
 +     *
 +     * @return the description
 +     */
-+    @NonNull Component getDescription();
++    Component getDescription();
 +
 +    /**
 +     * Gets if this datapack is required to be enabled.
@@ -60,14 +61,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the compatibility of the pack
 +     */
-+    @NonNull Compatibility getCompatibility();
++    Compatibility getCompatibility();
 +
 +    /**
 +     * Gets the set of required features for this datapack.
 +     *
 +     * @return the set of required features
 +     */
-+    @NonNull @Unmodifiable Set<FeatureFlag> getRequiredFeatures();
++    @Unmodifiable Set<FeatureFlag> getRequiredFeatures();
 +
 +    /**
 +     * Gets the enabled state of this pack.
@@ -91,7 +92,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the pack source
 +     */
-+    @NonNull DatapackSource getSource();
++    DatapackSource getSource();
 +
 +    /**
 +     * Computes the component vanilla Minecraft uses
@@ -101,7 +102,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new component
 +     */
 +    @Contract(pure = true, value = "-> new")
-+    @NonNull Component computeDisplayName();
++    Component computeDisplayName();
 +
 +    enum Compatibility {
 +        TOO_OLD,
@@ -117,12 +118,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.datapack;
 +
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+
 +import java.util.Collection;
-+import org.checkerframework.checker.nullness.qual.Nullable;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
++@NullMarked
 +public interface DatapackManager {
 +
 +    /**
@@ -140,7 +141,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param name the name/id of the datapack
 +     * @return the datapack, or null if not found
 +     */
-+    @Nullable Datapack getPack(@NonNull String name);
++    @Nullable Datapack getPack(String name);
 +
 +    /**
 +     * Gets the available datapacks. May require calling {@link #refreshPacks()} before
@@ -148,7 +149,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return all the packs known to the server
 +     */
-+    @NonNull @Unmodifiable Collection<Datapack> getPacks();
++    @Unmodifiable Collection<Datapack> getPacks();
 +
 +    /**
 +     * Gets the enabled datapacks. May require calling {@link #refreshPacks()} before
@@ -156,7 +157,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return all the packs which are currently enabled
 +     */
-+    @NonNull @Unmodifiable Collection<Datapack> getEnabledPacks();
++    @Unmodifiable Collection<Datapack> getEnabledPacks();
 +}
 diff --git a/src/main/java/io/papermc/paper/datapack/DatapackSource.java b/src/main/java/io/papermc/paper/datapack/DatapackSource.java
 new file mode 100644
@@ -166,9 +167,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.datapack;
 +
++import org.jspecify.annotations.NullMarked;
++
 +/**
 + * Source of a datapack.
 + */
++@NullMarked
 +public sealed interface DatapackSource permits DatapackSourceImpl {
 +
 +    DatapackSource DEFAULT = create("default");
@@ -190,8 +194,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.datapack;
 +
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
++@NullMarked
 +record DatapackSourceImpl(String name) implements DatapackSource {
 +
 +    @Override

patches/api/Add-moon-phase-API.patch

@@ -12,11 +12,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.world;
 +
-+import org.jetbrains.annotations.NotNull;
-+
 +import java.util.HashMap;
 +import java.util.Map;
++import org.jspecify.annotations.NullMarked;
 +
++@NullMarked
 +public enum MoonPhase {
 +    FULL_MOON(0L),
 +    WANING_GIBBOUS(1L),
@@ -29,20 +29,19 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +    private final long day;
 +
-+    MoonPhase(long day) {
++    MoonPhase(final long day) {
 +        this.day = day;
 +    }
 +
 +    private static final Map<Long, MoonPhase> BY_DAY = new HashMap<>();
 +
 +    static {
-+        for (MoonPhase phase : values()) {
++        for (final MoonPhase phase : values()) {
 +            BY_DAY.put(phase.day, phase);
 +        }
 +    }
 +
-+    @NotNull
++    public static MoonPhase getPhase(final long day) {
-+    public static MoonPhase getPhase(long day) {
 +        return BY_DAY.get(day % 8L);
 +    }
 +}

patches/api/Add-more-advancement-API.patch

@@ -20,8 +20,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import net.kyori.adventure.util.Index;
 +import org.bukkit.NamespacedKey;
 +import org.bukkit.inventory.ItemStack;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Describes the display of an advancement.
@@ -29,6 +29,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * The display is used in the chat, in the toast messages and the advancements
 + * screen.
 + */
++@NullMarked
 +public interface AdvancementDisplay {
 +
 +    /**
@@ -39,7 +40,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the frame type
 +     */
-+    @NotNull
 +    Frame frame();
 +
 +    /**
@@ -47,7 +47,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the title
 +     */
-+    @NotNull
 +    Component title();
 +
 +    /**
@@ -55,7 +54,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the description
 +     */
-+    @NotNull
 +    Component description();
 +
 +    /**
@@ -63,7 +61,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return a copy of the icon
 +     */
-+    @NotNull
 +    ItemStack icon();
 +
 +    /**
@@ -104,8 +101,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the background texture path
 +     */
-+    @Nullable
++    @Nullable NamespacedKey backgroundPath();
-+    NamespacedKey backgroundPath();
 +
 +    /**
 +     * Gets the formatted display name for this display. This
@@ -115,7 +111,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the display name
 +     * @see org.bukkit.advancement.Advancement#displayName()
 +     */
-+    @NotNull Component displayName();
++    Component displayName();
 +
 +    /**
 +     * Defines how the {@link #icon()} appears in the advancements screen and
@@ -148,7 +144,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        private final String name;
 +        private final TextColor color;
 +
-+        Frame(String name, TextColor color) {
++        Frame(final String name, final TextColor color) {
 +            this.name = name;
 +            this.color = color;
 +        }
@@ -158,7 +154,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         *
 +         * @return the text color
 +         */
-+        @NotNull
 +        public TextColor color() {
 +            return this.color;
 +        }
@@ -171,7 +166,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @return the toast message key
 +         */
 +        @Override
-+        @NotNull
 +        public String translationKey() {
 +            return "advancements.toast." + this.name;
 +        }

patches/api/Add-villager-reputation-API.patch

@@ -13,10 +13,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package com.destroystokyo.paper.entity.villager;
 +
 +import com.google.common.base.Preconditions;
-+
 +import java.util.EnumMap;
 +import java.util.Map;
-+import org.jetbrains.annotations.NotNull;
 +import org.jspecify.annotations.NullMarked;
 +
 +/**
@@ -31,7 +29,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        this(new EnumMap<>(ReputationType.class));
 +    }
 +
-+    public Reputation(Map<ReputationType, Integer> reputation) {
++    public Reputation(final Map<ReputationType, Integer> reputation) {
 +        Preconditions.checkNotNull(reputation, "reputation cannot be null");
 +        this.reputation = reputation;
 +    }
@@ -42,7 +40,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param type The {@link ReputationType type} of reputation to get.
 +     * @return The value of the {@link ReputationType type}.
 +     */
-+    public int getReputation(ReputationType type) {
++    public int getReputation(final ReputationType type) {
 +        Preconditions.checkNotNull(type, "the reputation type cannot be null");
 +        return this.reputation.getOrDefault(type, 0);
 +    }
@@ -53,7 +51,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param type The {@link ReputationType type} of reputation to set.
 +     * @param value The value of the {@link ReputationType type}.
 +     */
-+    public void setReputation(ReputationType type, int value) {
++    public void setReputation(final ReputationType type, final int value) {
 +        Preconditions.checkNotNull(type, "the reputation type cannot be null");
 +        this.reputation.put(type, value);
 +    }
@@ -64,7 +62,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param type The {@link ReputationType type} to check
 +     * @return If there is a value for this {@link ReputationType type} set.
 +     */
-+    public boolean hasReputationSet(ReputationType type) {
++    public boolean hasReputationSet(final ReputationType type) {
 +        return this.reputation.containsKey(type);
 +    }
 +}

patches/api/Adventure.patch

@@ -101,13 +101,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import net.kyori.adventure.text.Component;
 +import org.bukkit.entity.Player;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A chat renderer is responsible for rendering chat messages sent by {@link Player}s to the server.
 + */
++@NullMarked
 +@FunctionalInterface
 +public interface ChatRenderer {
++
 +    /**
 +     * Renders a chat message. This will be called once for each receiving {@link Audience}.
 +     *
@@ -118,15 +120,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a rendered chat message
 +     */
 +    @ApiStatus.OverrideOnly
-+    @NotNull
++    Component render(Player source, Component sourceDisplayName, Component message, Audience viewer);
-+    Component render(@NotNull Player source, @NotNull Component sourceDisplayName, @NotNull Component message, @NotNull Audience viewer);
 +
 +    /**
 +     * Create a new instance of the default {@link ChatRenderer}.
 +     *
 +     * @return a new {@link ChatRenderer}
 +     */
-+    @NotNull
 +    static ChatRenderer defaultRenderer() {
 +        return new ViewerUnawareImpl.Default((source, sourceDisplayName, message) -> Component.translatable("chat.type.text", sourceDisplayName, message));
 +    }
@@ -142,8 +142,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param renderer the viewer unaware renderer
 +     * @return a new {@link ChatRenderer}
 +     */
-+    @NotNull
++    static ChatRenderer viewerUnaware(final ViewerUnaware renderer) {
-+    static ChatRenderer viewerUnaware(final @NotNull ViewerUnaware renderer) {
 +        return new ViewerUnawareImpl(renderer);
 +    }
 +
@@ -153,6 +152,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see ChatRenderer#viewerUnaware(ViewerUnaware)
 +     */
 +    interface ViewerUnaware {
++
 +        /**
 +         * Renders a chat message.
 +         *
@@ -162,8 +162,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @return a rendered chat message
 +         */
 +        @ApiStatus.OverrideOnly
-+        @NotNull
++        Component render(Player source, Component sourceDisplayName, Component message);
-+        Component render(@NotNull Player source, @NotNull Component sourceDisplayName, @NotNull Component message);
 +    }
 +}
 diff --git a/src/main/java/io/papermc/paper/chat/ViewerUnawareImpl.java b/src/main/java/io/papermc/paper/chat/ViewerUnawareImpl.java
@@ -177,9 +176,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import net.kyori.adventure.audience.Audience;
 +import net.kyori.adventure.text.Component;
 +import org.bukkit.entity.Player;
-+import org.jetbrains.annotations.NotNull;
++import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
++@ApiStatus.Internal
++@NullMarked
 +sealed class ViewerUnawareImpl implements ChatRenderer, ChatRenderer.ViewerUnaware permits ViewerUnawareImpl.Default {
 +    private final ViewerUnaware unaware;
 +    private @Nullable Component message;
@@ -189,12 +191,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    @Override
-+    public @NotNull Component render(final @NotNull Player source, final @NotNull Component sourceDisplayName, final @NotNull Component message, final @NotNull Audience viewer) {
++    public Component render(final Player source, final Component sourceDisplayName, final Component message, final Audience viewer) {
 +        return this.render(source, sourceDisplayName, message);
 +    }
 +
 +    @Override
-+    public @NotNull Component render(final @NotNull Player source, final @NotNull Component sourceDisplayName, final @NotNull Component message) {
++    public Component render(final Player source, final Component sourceDisplayName, final Component message) {
 +        if (this.message == null) {
 +            this.message = this.unaware.render(source, sourceDisplayName, message);
 +        }
@@ -585,6 +587,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.text;
 +
++import java.io.IOException;
 +import net.kyori.adventure.text.Component;
 +import net.kyori.adventure.text.flattener.ComponentFlattener;
 +import net.kyori.adventure.text.format.NamedTextColor;
@@ -595,15 +598,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.Bukkit;
 +import org.bukkit.command.CommandSender;
 +import org.bukkit.entity.Entity;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
-+
-+import java.io.IOException;
 +
 +/**
 + * Paper API-specific methods for working with {@link Component}s and related.
 + */
++@NullMarked
 +public final class PaperComponents {
++
 +    private PaperComponents() {
 +        throw new RuntimeException("PaperComponents is not to be instantiated!");
 +    }
@@ -633,7 +636,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the resolved component
 +     * @throws IOException if a syntax error tripped during resolving
 +     */
-+    public static @NotNull Component resolveWithContext(@NotNull Component input, @Nullable CommandSender context, @Nullable Entity scoreboardSubject) throws IOException {
++    public static Component resolveWithContext(final Component input, final @Nullable CommandSender context, final @Nullable Entity scoreboardSubject) throws IOException {
 +        return resolveWithContext(input, context, scoreboardSubject, true);
 +    }
 +
@@ -664,7 +667,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the resolved component
 +     * @throws IOException if a syntax error tripped during resolving
 +     */
-+    public static @NotNull Component resolveWithContext(@NotNull Component input, @Nullable CommandSender context, @Nullable Entity scoreboardSubject, boolean bypassPermissions) throws IOException {
++    @SuppressWarnings("deprecation") // using unsafe as a bridge
++    public static Component resolveWithContext(final Component input, final @Nullable CommandSender context, final @Nullable Entity scoreboardSubject, final boolean bypassPermissions) throws IOException {
 +        return Bukkit.getUnsafe().resolveWithContext(input, context, scoreboardSubject, bypassPermissions);
 +    }
 +
@@ -673,7 +677,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return a component flattener
 +     */
-+    public static @NotNull ComponentFlattener flattener() {
++    @SuppressWarnings("deprecation") // using unsafe as a bridge
++    public static ComponentFlattener flattener() {
 +        return Bukkit.getUnsafe().componentFlattener();
 +    }
 +
@@ -688,7 +693,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @deprecated will be removed in adventure 5.0.0, use {@link PlainTextComponentSerializer#plainText()}
 +     */
 +    @Deprecated(forRemoval = true, since = "1.18.1")
-+    public static @NotNull PlainComponentSerializer plainSerializer() {
++    public static PlainComponentSerializer plainSerializer() {
 +        return Bukkit.getUnsafe().plainComponentSerializer();
 +    }
 +
@@ -703,7 +708,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @deprecated use {@link PlainTextComponentSerializer#plainText()}
 +     */
 +    @Deprecated(forRemoval = true, since = "1.18.2")
-+    public static @NotNull PlainTextComponentSerializer plainTextSerializer() {
++    public static PlainTextComponentSerializer plainTextSerializer() {
 +        return Bukkit.getUnsafe().plainTextSerializer();
 +    }
 +
@@ -719,7 +724,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @deprecated use {@link GsonComponentSerializer#gson()}
 +     */
 +    @Deprecated(forRemoval = true, since = "1.18.2")
-+    public static @NotNull GsonComponentSerializer gsonSerializer() {
++    public static GsonComponentSerializer gsonSerializer() {
 +        return Bukkit.getUnsafe().gsonComponentSerializer();
 +    }
 +
@@ -736,7 +741,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @deprecated use {@link GsonComponentSerializer#colorDownsamplingGson()}
 +     */
 +    @Deprecated(forRemoval = true, since = "1.18.2")
-+    public static @NotNull GsonComponentSerializer colorDownsamplingGsonSerializer() {
++    public static GsonComponentSerializer colorDownsamplingGsonSerializer() {
 +        return Bukkit.getUnsafe().colorDownsamplingGsonComponentSerializer();
 +    }
 +
@@ -756,7 +761,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @deprecated use {@link LegacyComponentSerializer#legacySection()}
 +     */
 +    @Deprecated(forRemoval = true, since = "1.18.2")
-+    public static @NotNull LegacyComponentSerializer legacySectionSerializer() {
++    public static LegacyComponentSerializer legacySectionSerializer() {
 +        return Bukkit.getUnsafe().legacyComponentSerializer();
 +    }
 +}

patches/api/AsyncTabCompleteEvent.patch

@@ -362,9 +362,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.util;
 +
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.jetbrains.annotations.NotNull;
-+
 +import java.util.AbstractList;
 +import java.util.Iterator;
 +import java.util.List;
@@ -372,6 +369,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.RandomAccess;
 +import java.util.function.Function;
 +import java.util.function.Predicate;
++import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +import static com.google.common.base.Preconditions.checkNotNull;
 +
@@ -381,7 +380,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <F> backing list element type
 + * @param <T> transformed list element type
 + */
++@NullMarked
++@ApiStatus.Internal
 +public final class TransformingRandomAccessList<F, T> extends AbstractList<T> implements RandomAccess {
++
 +    final List<F> fromList;
 +    final Function<? super F, ? extends T> toFunction;
 +    final Function<? super T, ? extends F> fromFunction;
@@ -394,9 +396,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param fromFunction function mapping transformed list element type to backing list element type
 +     */
 +    public TransformingRandomAccessList(
-+        final @NonNull List<F> fromList,
++        final List<F> fromList,
-+        final @NonNull Function<? super F, ? extends T> toFunction,
++        final Function<? super F, ? extends T> toFunction,
-+        final @NonNull Function<? super T, ? extends F> fromFunction
++        final Function<? super T, ? extends F> fromFunction
 +    ) {
 +        this.fromList = checkNotNull(fromList);
 +        this.toFunction = checkNotNull(toFunction);
@@ -409,25 +411,25 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    @Override
-+    public T get(int index) {
++    public T get(final int index) {
 +        return this.toFunction.apply(this.fromList.get(index));
 +    }
 +
 +    @Override
-+    public @NotNull Iterator<T> iterator() {
++    public Iterator<T> iterator() {
 +        return this.listIterator();
 +    }
 +
 +    @Override
-+    public @NotNull ListIterator<T> listIterator(int index) {
++    public ListIterator<T> listIterator(final int index) {
-+        return new TransformedListIterator<F, T>(this.fromList.listIterator(index)) {
++        return new TransformedListIterator<>(this.fromList.listIterator(index)) {
 +            @Override
-+            T transform(F from) {
++            T transform(final F from) {
 +                return TransformingRandomAccessList.this.toFunction.apply(from);
 +            }
 +
 +            @Override
-+            F transformBack(T from) {
++            F transformBack(final T from) {
 +                return TransformingRandomAccessList.this.fromFunction.apply(from);
 +            }
 +        };
@@ -439,13 +441,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    @Override
-+    public boolean removeIf(Predicate<? super T> filter) {
++    public boolean removeIf(final Predicate<? super T> filter) {
 +        checkNotNull(filter);
 +        return this.fromList.removeIf(element -> filter.test(this.toFunction.apply(element)));
 +    }
 +
 +    @Override
-+    public T remove(int index) {
++    public T remove(final int index) {
 +        return this.toFunction.apply(this.fromList.remove(index));
 +    }
 +
@@ -455,19 +457,20 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    @Override
-+    public T set(int i, T t) {
++    public T set(final int i, final T t) {
 +        return this.toFunction.apply(this.fromList.set(i, this.fromFunction.apply(t)));
 +    }
 +
 +    @Override
-+    public void add(int i, T t) {
++    public void add(final int i, final T t) {
 +        this.fromList.add(i, this.fromFunction.apply(t));
 +    }
 +
-+    static abstract class TransformedListIterator<F, T> implements ListIterator<T>, Iterator<T> {
++    abstract static class TransformedListIterator<F, T> implements ListIterator<T>, Iterator<T> {
++
 +        final Iterator<F> backingIterator;
 +
-+        TransformedListIterator(ListIterator<F> backingIterator) {
++        TransformedListIterator(final ListIterator<F> backingIterator) {
 +            this.backingIterator = checkNotNull((Iterator<F>) backingIterator);
 +        }
 +
@@ -475,7 +478,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +            return cast(this.backingIterator);
 +        }
 +
-+        static <A> ListIterator<A> cast(Iterator<A> iterator) {
++        static <A> ListIterator<A> cast(final Iterator<A> iterator) {
 +            return (ListIterator<A>) iterator;
 +        }
 +
@@ -500,12 +503,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        }
 +
 +        @Override
-+        public void set(T element) {
++        public void set(final T element) {
 +            this.backingIterator().set(this.transformBack(element));
 +        }
 +
 +        @Override
-+        public void add(T element) {
++        public void add(final T element) {
 +            this.backingIterator().add(this.transformBack(element));
 +        }
 +

patches/api/Basic-PlayerProfile-API.patch

@@ -16,20 +16,21 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Collection;
 +import java.util.Set;
 +import java.util.UUID;
-+
 +import java.util.concurrent.CompletableFuture;
 +import org.bukkit.profile.PlayerTextures;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Represents a players profile for the game, such as UUID, Name, and textures.
 + */
++@NullMarked
 +public interface PlayerProfile extends org.bukkit.profile.PlayerProfile {
 +
 +    /**
 +     * @return The players name, if set
 +     */
++    @Override
 +    @Nullable
 +    String getName();
 +
@@ -39,14 +40,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param name The new Name
 +     * @return The previous Name
 +     */
-+    @NotNull
 +    @Deprecated(forRemoval = true, since = "1.18.1")
 +    String setName(@Nullable String name);
 +
 +    /**
 +     * @return The players unique identifier, if set
 +     */
-+    @Nullable UUID getId();
++    @Nullable
++    UUID getId();
 +
 +    /**
 +     * Sets this profiles UUID
@@ -54,8 +55,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param uuid The new UUID
 +     * @return The previous UUID
 +     */
-+    @Nullable
 +    @Deprecated(forRemoval = true, since = "1.18.1")
++    @Nullable
 +    UUID setId(@Nullable UUID uuid);
 +
 +    /**
@@ -65,7 +66,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the textures, not <code>null</code>
 +     */
-+    @NotNull
++    @Override
 +    PlayerTextures getTextures();
 +
 +    /**
@@ -74,16 +75,18 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param textures the textures to copy, or <code>null</code> to clear the
 +     * textures
 +     */
++    @Override
 +    void setTextures(@Nullable PlayerTextures textures);
 +
 +    /**
 +     * @return A Mutable set of this players properties, such as textures.
 +     * Values specified here are subject to implementation details.
 +     */
-+    @NotNull Set<ProfileProperty> getProperties();
++    Set<ProfileProperty> getProperties();
 +
 +    /**
 +     * Check if the Profile has the specified property
++     *
 +     * @param property Property name to check
 +     * @return If the property is set
 +     */
@@ -95,17 +98,19 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param property Property to set.
 +     * @throws IllegalArgumentException if setting the property results in more than 16 properties
 +     */
-+    void setProperty(@NotNull ProfileProperty property);
++    void setProperty(ProfileProperty property);
 +
 +    /**
 +     * Sets multiple properties. If any of the set properties already exist, it will be replaced
++     *
 +     * @param properties The properties to set
 +     * @throws IllegalArgumentException if the number of properties exceeds 16
 +     */
-+    void setProperties(@NotNull Collection<ProfileProperty> properties);
++    void setProperties(Collection<ProfileProperty> properties);
 +
 +    /**
 +     * Removes a specific property from this profile
++     *
 +     * @param property The property to remove
 +     * @return If a property was removed
 +     */
@@ -113,22 +118,24 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +    /**
 +     * Removes a specific property from this profile
++     *
 +     * @param property The property to remove
 +     * @return If a property was removed
 +     */
-+    default boolean removeProperty(@NotNull ProfileProperty property) {
++    default boolean removeProperty(final ProfileProperty property) {
-+        return removeProperty(property.getName());
++        return this.removeProperty(property.getName());
 +    }
 +
 +    /**
 +     * Removes all properties in the collection
++     *
 +     * @param properties The properties to remove
 +     * @return If any property was removed
 +     */
-+    default boolean removeProperties(@NotNull Collection<ProfileProperty> properties) {
++    default boolean removeProperties(final Collection<ProfileProperty> properties) {
 +        boolean removed = false;
-+        for (ProfileProperty property : properties) {
++        for (final ProfileProperty property : properties) {
-+            if (removeProperty(property)) {
++            if (this.removeProperty(property)) {
 +                removed = true;
 +            }
 +        }
@@ -143,6 +150,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    /**
 +     * @return If the profile is now complete (has UUID and Name)
 +     */
++    @Override
 +    boolean isComplete();
 +
 +    /**
@@ -175,21 +183,23 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    /**
 +     * If this profile is not complete, then make the API call to complete it.
 +     * This is a blocking operation and should be done asynchronously.
-+     *
++     * <p>
 +     * This will also complete textures. If you do not want to load textures, use {{@link #complete(boolean)}}
++     *
 +     * @return If the profile is now complete (has UUID and Name) (if you get rate limited, this operation may fail)
 +     */
 +    default boolean complete() {
-+        return complete(true);
++        return this.complete(true);
 +    }
 +
 +    /**
 +     * If this profile is not complete, then make the API call to complete it.
 +     * This is a blocking operation and should be done asynchronously.
-+     *
++     * <p>
 +     * Optionally will also fill textures.
-+     *
++     * <p>
 +     * Online mode will be automatically determined
++     *
 +     * @param textures controls if we should fill the profile with texture properties
 +     * @return If the profile is now complete (has UUID and Name) (if you get rate limited, this operation may fail)
 +     */
@@ -198,8 +208,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    /**
 +     * If this profile is not complete, then make the API call to complete it.
 +     * This is a blocking operation and should be done asynchronously.
-+     *
++     * <p>
 +     * Optionally will also fill textures.
++     *
 +     * @param textures controls if we should fill the profile with texture properties
 +     * @param onlineMode Treat this server as online mode or not
 +     * @return If the profile is now complete (has UUID and Name) (if you get rate limited, this operation may fail)
@@ -235,14 +246,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * </pre>
 +     */
 +    @Override
-+    @NotNull CompletableFuture<PlayerProfile> update();
++    CompletableFuture<PlayerProfile> update();
 +
 +    /**
 +     * Whether this Profile has textures associated to it
++     *
 +     * @return If it has a textures property
 +     */
 +    default boolean hasTextures() {
-+        return hasProperty("textures");
++        return this.hasProperty("textures");
 +    }
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/profile/ProfileProperty.java b/src/main/java/com/destroystokyo/paper/profile/ProfileProperty.java
@@ -254,24 +266,25 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package com.destroystokyo.paper.profile;
 +
 +import com.google.common.base.Preconditions;
-+
 +import java.util.Objects;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Represents a property on a {@link PlayerProfile}
 + */
++@NullMarked
 +public final class ProfileProperty {
++
 +    private final String name;
 +    private final String value;
-+    private final String signature;
++    private final @Nullable String signature;
 +
-+    public ProfileProperty(@NotNull String name, @NotNull String value) {
++    public ProfileProperty(final String name, final String value) {
 +        this(name, value, null);
 +    }
 +
-+    public ProfileProperty(@NotNull String name, @NotNull String value, @Nullable String signature) {
++    public ProfileProperty(final String name, final String value, final @Nullable String signature) {
 +        this.name = Preconditions.checkNotNull(name, "ProfileProperty name can not be null");
 +        this.value = Preconditions.checkNotNull(value, "ProfileProperty value can not be null");
 +        this.signature = signature;
@@ -283,25 +296,22 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    /**
 +     * @return The property name, ie "textures"
 +     */
-+    @NotNull
 +    public String getName() {
-+        return name;
++        return this.name;
 +    }
 +
 +    /**
 +     * @return The property value, likely to be base64 encoded
 +     */
-+    @NotNull
 +    public String getValue() {
-+        return value;
++        return this.value;
 +    }
 +
 +    /**
 +     * @return A signature from Mojang for signed properties
 +     */
-+    @Nullable
++    public @Nullable String getSignature() {
-+    public String getSignature() {
++        return this.signature;
-+        return signature;
 +    }
 +
 +    /**
@@ -312,18 +322,18 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    @Override
-+    public boolean equals(Object o) {
++    public boolean equals(final @Nullable Object o) {
 +        if (this == o) return true;
-+        if (o == null || getClass() != o.getClass()) return false;
++        if (o == null || this.getClass() != o.getClass()) return false;
-+        ProfileProperty that = (ProfileProperty) o;
++        final ProfileProperty that = (ProfileProperty) o;
-+        return Objects.equals(name, that.name) &&
++        return Objects.equals(this.name, that.name) &&
-+                Objects.equals(value, that.value) &&
++            Objects.equals(this.value, that.value) &&
-+                Objects.equals(signature, that.signature);
++            Objects.equals(this.signature, that.signature);
 +    }
 +
 +    @Override
 +    public int hashCode() {
-+        return Objects.hash(name);
++        return Objects.hash(this.name);
 +    }
 +}
 diff --git a/src/main/java/org/bukkit/Bukkit.java b/src/main/java/org/bukkit/Bukkit.java

patches/api/Brigadier-based-command-API.patch

@@ -512,14 +512,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Collections;
 +import org.bukkit.command.CommandSender;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Implementing this interface allows for easily creating "Bukkit-style" {@code String[] args} commands.
 + * The implementation handles converting the command to a representation compatible with Brigadier on registration, usually in the form of {@literal /commandlabel <greedy_string>}.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@FunctionalInterface
 +public interface BasicCommand {
 +
@@ -530,7 +531,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param args the arguments of the command ignoring repeated spaces
 +     */
 +    @ApiStatus.OverrideOnly
-+    void execute(@NotNull CommandSourceStack commandSourceStack, @NotNull String[] args);
++    void execute(CommandSourceStack commandSourceStack, String[] args);
 +
 +    /**
 +     * Suggests possible completions for the given command {@link CommandSourceStack} and arguments.
@@ -540,7 +541,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a collection of suggestions
 +     */
 +    @ApiStatus.OverrideOnly
-+    default @NotNull Collection<String> suggest(final @NotNull CommandSourceStack commandSourceStack, final @NotNull String[] args) {
++    default Collection<String> suggest(final CommandSourceStack commandSourceStack, final String[] args) {
 +        return Collections.emptyList();
 +    }
 +
@@ -552,8 +553,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see #permission()
 +     */
 +    @ApiStatus.OverrideOnly
-+    default boolean canUse(final @NotNull CommandSender sender) {
++    default boolean canUse(final CommandSender sender) {
-+        return this.permission() == null || sender.hasPermission(this.permission());
++        final String permission = this.permission();
++        return permission == null || sender.hasPermission(permission);
 +    }
 +
 +    /**
@@ -598,8 +600,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.command.CommandSender;
 +import org.bukkit.entity.Entity;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * The command source type for Brigadier commands registered using Paper API.
@@ -613,8 +615,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * exist yet, or no specific sender is available. Methods on such a {@link CommandSender}
 + * will either have no effect or throw an {@link UnsupportedOperationException}.</p>
 + */
-+@ApiStatus.NonExtendable
 +@ApiStatus.Experimental
++@NullMarked
++@ApiStatus.NonExtendable
 +public interface CommandSourceStack {
 +
 +    /**
@@ -622,7 +625,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return a cloned location instance.
 +     */
-+    @NotNull Location getLocation();
++    Location getLocation();
 +
 +    /**
 +     * Gets the command sender that executed this command.
@@ -631,7 +634,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the command sender instance
 +     */
-+    @NotNull CommandSender getSender();
++    CommandSender getSender();
 +
 +    /**
 +     * Gets the entity that executes this command.
@@ -664,9 +667,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Collections;
 +import java.util.Set;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
-+import org.jetbrains.annotations.Nullable;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * The registrar for custom commands. Supports Brigadier commands and {@link BasicCommand}.
@@ -709,6 +712,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see io.papermc.paper.plugin.lifecycle.event.types.LifecycleEvents#COMMANDS
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface Commands extends Registrar {
 +
@@ -718,7 +722,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param literal literal name
 +     * @return a new builder instance
 +     */
-+    static @NotNull LiteralArgumentBuilder<CommandSourceStack> literal(final @NotNull String literal) {
++    static LiteralArgumentBuilder<CommandSourceStack> literal(final String literal) {
 +        return LiteralArgumentBuilder.literal(literal);
 +    }
 +
@@ -730,7 +734,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T>          the generic type of the argument value
 +     * @return a new required argument builder
 +     */
-+    static <T> @NotNull RequiredArgumentBuilder<CommandSourceStack, T> argument(final @NotNull String name, final @NotNull ArgumentType<T> argumentType) {
++    static <T> RequiredArgumentBuilder<CommandSourceStack, T> argument(final String name, final ArgumentType<T> argumentType) {
 +        return RequiredArgumentBuilder.argument(name, argumentType);
 +    }
 +
@@ -754,7 +758,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the dispatcher instance
 +     */
 +    @ApiStatus.Experimental
-+    @NotNull CommandDispatcher<CommandSourceStack> getDispatcher();
++    CommandDispatcher<CommandSourceStack> getDispatcher();
 +
 +    /**
 +     * Registers a command for the current plugin context.
@@ -768,7 +772,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param node the built literal command node
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    default @Unmodifiable @NotNull Set<String> register(final @NotNull LiteralCommandNode<CommandSourceStack> node) {
++    default @Unmodifiable Set<String> register(final LiteralCommandNode<CommandSourceStack> node) {
 +        return this.register(node, null, Collections.emptyList());
 +    }
 +
@@ -785,7 +789,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param description the help description for the root literal node
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    default @Unmodifiable @NotNull Set<String> register(final @NotNull LiteralCommandNode<CommandSourceStack> node, final @Nullable String description) {
++    default @Unmodifiable Set<String> register(final LiteralCommandNode<CommandSourceStack> node, final @Nullable String description) {
 +        return this.register(node, description, Collections.emptyList());
 +    }
 +
@@ -802,7 +806,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param aliases a collection of aliases to register the literal node's command to
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    default @Unmodifiable @NotNull Set<String> register(final @NotNull LiteralCommandNode<CommandSourceStack> node, final @NotNull Collection<String> aliases) {
++    default @Unmodifiable Set<String> register(final LiteralCommandNode<CommandSourceStack> node, final Collection<String> aliases) {
 +        return this.register(node, null, aliases);
 +    }
 +
@@ -820,7 +824,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param aliases     a collection of aliases to register the literal node's command to
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    @Unmodifiable @NotNull Set<String> register(@NotNull LiteralCommandNode<CommandSourceStack> node, @Nullable String description, @NotNull Collection<String> aliases);
++    @Unmodifiable Set<String> register(LiteralCommandNode<CommandSourceStack> node, @Nullable String description, Collection<String> aliases);
 +
 +    /**
 +     * Registers a command for a plugin.
@@ -837,7 +841,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param aliases     a collection of aliases to register the literal node's command to
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    @Unmodifiable @NotNull Set<String> register(@NotNull PluginMeta pluginMeta, @NotNull LiteralCommandNode<CommandSourceStack> node, @Nullable String description, @NotNull Collection<String> aliases);
++    @Unmodifiable Set<String> register(PluginMeta pluginMeta, LiteralCommandNode<CommandSourceStack> node, @Nullable String description, Collection<String> aliases);
 +
 +    /**
 +     * This allows configuring the registration of your command, which is not intended for public use.
@@ -854,7 +858,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * See {@link CommandRegistrationFlag} for a more indepth explanation of this method's use-case.
 +     */
 +    @ApiStatus.Internal
-+    @Unmodifiable @NotNull Set<String> registerWithFlags(@NotNull PluginMeta pluginMeta, @NotNull LiteralCommandNode<CommandSourceStack> node, @Nullable String description, @NotNull Collection<String> aliases, @NotNull Set<CommandRegistrationFlag> flags);
++    @Unmodifiable Set<String> registerWithFlags(PluginMeta pluginMeta, LiteralCommandNode<CommandSourceStack> node, @Nullable String description, Collection<String> aliases, Set<CommandRegistrationFlag> flags);
 +
 +    /**
 +     * Registers a command under the same logic as {@link Commands#register(LiteralCommandNode, String, Collection)}.
@@ -863,7 +867,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param basicCommand the basic command instance to register
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    default @Unmodifiable @NotNull Set<String> register(final @NotNull String label, final @NotNull BasicCommand basicCommand) {
++    default @Unmodifiable Set<String> register(final String label, final BasicCommand basicCommand) {
 +        return this.register(label, null, Collections.emptyList(), basicCommand);
 +    }
 +
@@ -875,7 +879,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param basicCommand the basic command instance to register
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    default @Unmodifiable @NotNull Set<String> register(final @NotNull String label, final @Nullable String description, final @NotNull BasicCommand basicCommand) {
++    default @Unmodifiable Set<String> register(final String label, final @Nullable String description, final BasicCommand basicCommand) {
 +        return this.register(label, description, Collections.emptyList(), basicCommand);
 +    }
 +
@@ -887,7 +891,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param basicCommand the basic command instance to register
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    default @Unmodifiable @NotNull Set<String> register(final @NotNull String label, final @NotNull Collection<String> aliases, final @NotNull BasicCommand basicCommand) {
++    default @Unmodifiable Set<String> register(final String label, final Collection<String> aliases, final BasicCommand basicCommand) {
 +        return this.register(label, null, aliases, basicCommand);
 +    }
 +
@@ -900,7 +904,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param basicCommand the basic command instance to register
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    @Unmodifiable @NotNull Set<String> register(@NotNull String label, @Nullable String description, @NotNull Collection<String> aliases, @NotNull BasicCommand basicCommand);
++    @Unmodifiable Set<String> register(String label, @Nullable String description, Collection<String> aliases, BasicCommand basicCommand);
 +
 +    /**
 +     * Registers a command under the same logic as {@link Commands#register(PluginMeta, LiteralCommandNode, String, Collection)}.
@@ -912,7 +916,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param basicCommand the basic command instance to register
 +     * @return successfully registered root command labels (including aliases and namespaced variants)
 +     */
-+    @Unmodifiable @NotNull Set<String> register(@NotNull PluginMeta pluginMeta, @NotNull String label, @Nullable String description, @NotNull Collection<String> aliases, @NotNull BasicCommand basicCommand);
++    @Unmodifiable Set<String> register(PluginMeta pluginMeta, String label, @Nullable String description, Collection<String> aliases, BasicCommand basicCommand);
 +}
 diff --git a/src/main/java/io/papermc/paper/command/brigadier/MessageComponentSerializer.java b/src/main/java/io/papermc/paper/command/brigadier/MessageComponentSerializer.java
 new file mode 100644
@@ -926,12 +930,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import net.kyori.adventure.text.Component;
 +import net.kyori.adventure.text.serializer.ComponentSerializer;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A component serializer for converting between {@link Message} and {@link Component}.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface MessageComponentSerializer extends ComponentSerializer<Component, Component, Message> {
 +
@@ -940,7 +945,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return serializer instance
 +     */
-+    static @NotNull MessageComponentSerializer message() {
++    static MessageComponentSerializer message() {
 +        return MessageComponentSerializerHolder.PROVIDER.orElseThrow();
 +    }
 +}
@@ -998,7 +1003,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.scoreboard.Criteria;
 +import org.bukkit.scoreboard.DisplaySlot;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +import static io.papermc.paper.command.brigadier.argument.VanillaArgumentProvider.provider;
 +
@@ -1011,6 +1016,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * <p>{@link CustomArgumentType} is provided for customizing parsing or result types server-side, while sending the vanilla argument type to the client.</p>
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public final class ArgumentTypes {
 +
 +    /**
@@ -1019,7 +1025,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument that takes one entity
 +     */
-+    public static @NotNull ArgumentType<EntitySelectorArgumentResolver> entity() {
++    public static ArgumentType<EntitySelectorArgumentResolver> entity() {
 +        return provider().entity();
 +    }
 +
@@ -1029,7 +1035,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument that takes multiple entities
 +     */
-+    public static @NotNull ArgumentType<EntitySelectorArgumentResolver> entities() {
++    public static ArgumentType<EntitySelectorArgumentResolver> entities() {
 +        return provider().entities();
 +    }
 +
@@ -1039,7 +1045,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument that takes one player
 +     */
-+    public static @NotNull ArgumentType<PlayerSelectorArgumentResolver> player() {
++    public static ArgumentType<PlayerSelectorArgumentResolver> player() {
 +        return provider().player();
 +    }
 +
@@ -1049,7 +1055,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument that takes multiple players
 +     */
-+    public static @NotNull ArgumentType<PlayerSelectorArgumentResolver> players() {
++    public static ArgumentType<PlayerSelectorArgumentResolver> players() {
 +        return provider().players();
 +    }
 +
@@ -1059,7 +1065,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return player profile argument
 +     */
-+    public static @NotNull ArgumentType<PlayerProfileListResolver> playerProfiles() {
++    public static ArgumentType<PlayerProfileListResolver> playerProfiles() {
 +        return provider().playerProfiles();
 +    }
 +
@@ -1068,7 +1074,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return block position argument
 +     */
-+    public static @NotNull ArgumentType<BlockPositionResolver> blockPosition() {
++    public static ArgumentType<BlockPositionResolver> blockPosition() {
 +        return provider().blockPosition();
 +    }
 +
@@ -1078,7 +1084,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return fine position argument
 +     * @see #finePosition(boolean) to center whole numbers
 +     */
-+    public static @NotNull ArgumentType<FinePositionResolver> finePosition() {
++    public static ArgumentType<FinePositionResolver> finePosition() {
 +        return finePosition(false);
 +    }
 +
@@ -1088,7 +1094,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param centerIntegers if whole numbers should be centered (+0.5)
 +     * @return fine position argument
 +     */
-+    public static @NotNull ArgumentType<FinePositionResolver> finePosition(final boolean centerIntegers) {
++    public static ArgumentType<FinePositionResolver> finePosition(final boolean centerIntegers) {
 +        return provider().finePosition(centerIntegers);
 +    }
 +
@@ -1098,7 +1104,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<BlockState> blockState() {
++    public static ArgumentType<BlockState> blockState() {
 +        return provider().blockState();
 +    }
 +
@@ -1108,7 +1114,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<ItemStack> itemStack() {
++    public static ArgumentType<ItemStack> itemStack() {
 +        return provider().itemStack();
 +    }
 +
@@ -1117,7 +1123,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<ItemStackPredicate> itemPredicate() {
++    public static ArgumentType<ItemStackPredicate> itemPredicate() {
 +        return provider().itemStackPredicate();
 +    }
 +
@@ -1126,7 +1132,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<NamedTextColor> namedColor() {
++    public static ArgumentType<NamedTextColor> namedColor() {
 +        return provider().namedColor();
 +    }
 +
@@ -1135,7 +1141,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<Component> component() {
++    public static ArgumentType<Component> component() {
 +        return provider().component();
 +    }
 +
@@ -1144,7 +1150,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<Style> style() {
++    public static ArgumentType<Style> style() {
 +        return provider().style();
 +    }
 +
@@ -1155,7 +1161,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<SignedMessageResolver> signedMessage() {
++    public static ArgumentType<SignedMessageResolver> signedMessage() {
 +        return provider().signedMessage();
 +    }
 +
@@ -1164,7 +1170,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<DisplaySlot> scoreboardDisplaySlot() {
++    public static ArgumentType<DisplaySlot> scoreboardDisplaySlot() {
 +        return provider().scoreboardDisplaySlot();
 +    }
 +
@@ -1173,7 +1179,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<NamespacedKey> namespacedKey() {
++    public static ArgumentType<NamespacedKey> namespacedKey() {
 +        return provider().namespacedKey();
 +    }
 +
@@ -1183,7 +1189,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return argument
 +     */
 +    // include both key types as we are slowly moving to use adventure's key
-+    public static @NotNull ArgumentType<Key> key() {
++    public static ArgumentType<Key> key() {
 +        return provider().key();
 +    }
 +
@@ -1192,7 +1198,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<IntegerRangeProvider> integerRange() {
++    public static ArgumentType<IntegerRangeProvider> integerRange() {
 +        return provider().integerRange();
 +    }
 +
@@ -1201,7 +1207,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<DoubleRangeProvider> doubleRange() {
++    public static ArgumentType<DoubleRangeProvider> doubleRange() {
 +        return provider().doubleRange();
 +    }
 +
@@ -1210,7 +1216,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<World> world() {
++    public static ArgumentType<World> world() {
 +        return provider().world();
 +    }
 +
@@ -1219,16 +1225,16 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<GameMode> gameMode() {
++    public static ArgumentType<GameMode> gameMode() {
 +        return provider().gameMode();
 +    }
 +
 +    /**
-+     * A argument for getting a heightmap type.
++     * An argument for getting a heightmap type.
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<HeightMap> heightMap() {
++    public static ArgumentType<HeightMap> heightMap() {
 +        return provider().heightMap();
 +    }
 +
@@ -1237,7 +1243,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<UUID> uuid() {
++    public static ArgumentType<UUID> uuid() {
 +        return provider().uuid();
 +    }
 +
@@ -1246,7 +1252,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<Criteria> objectiveCriteria() {
++    public static ArgumentType<Criteria> objectiveCriteria() {
 +        return provider().objectiveCriteria();
 +    }
 +
@@ -1255,7 +1261,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<LookAnchor> entityAnchor() {
++    public static ArgumentType<LookAnchor> entityAnchor() {
 +        return provider().entityAnchor();
 +    }
 +
@@ -1271,7 +1277,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<Integer> time() {
++    public static ArgumentType<Integer> time() {
 +        return time(0);
 +    }
 +
@@ -1288,7 +1294,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param mintime The minimum time required for this argument.
 +     * @return argument
 +     */
-+    public static @NotNull ArgumentType<Integer> time(final int mintime) {
++    public static ArgumentType<Integer> time(final int mintime) {
 +        return provider().time(mintime);
 +    }
 +
@@ -1298,7 +1304,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return argument
 +     * @see Mirror
 +     */
-+    public static @NotNull ArgumentType<Mirror> templateMirror() {
++    public static ArgumentType<Mirror> templateMirror() {
 +        return provider().templateMirror();
 +    }
 +
@@ -1308,7 +1314,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return argument
 +     * @see StructureRotation
 +     */
-+    public static @NotNull ArgumentType<StructureRotation> templateRotation() {
++    public static ArgumentType<StructureRotation> templateRotation() {
 +        return provider().templateRotation();
 +    }
 +
@@ -1319,7 +1325,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return argument
 +     * @param <T> the registry value type
 +     */
-+    public static <T> @NotNull ArgumentType<T> resource(final @NotNull RegistryKey<T> registryKey) {
++    public static <T> ArgumentType<T> resource(final RegistryKey<T> registryKey) {
 +        return provider().resource(registryKey);
 +    }
 +
@@ -1331,7 +1337,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the registry value type
 +     * @see RegistryArgumentExtractor#getTypedKey(com.mojang.brigadier.context.CommandContext, RegistryKey, String)
 +     */
-+    public static <T> @NotNull ArgumentType<TypedKey<T>> resourceKey(final @NotNull RegistryKey<T> registryKey) {
++    public static <T> ArgumentType<TypedKey<T>> resourceKey(final RegistryKey<T> registryKey) {
 +        return provider().resourceKey(registryKey);
 +    }
 +
@@ -1355,7 +1361,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Collection;
 +import java.util.concurrent.CompletableFuture;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * An argument type that wraps around a native-to-vanilla argument type.
@@ -1370,6 +1376,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <N> type with an argument native to vanilla Minecraft (from {@link ArgumentTypes})
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public interface CustomArgumentType<T, N> extends ArgumentType<T> {
 +
 +    /**
@@ -1384,7 +1391,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @throws CommandSyntaxException if an error occurs while parsing
 +     */
 +    @Override
-+    @NotNull T parse(final @NotNull StringReader reader) throws CommandSyntaxException;
++    T parse(final StringReader reader) throws CommandSyntaxException;
 +
 +    /**
 +     * Gets the native type that this argument uses,
@@ -1392,7 +1399,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return native argument type
 +     */
-+    @NotNull ArgumentType<N> getNativeType();
++    ArgumentType<N> getNativeType();
 +
 +    /**
 +     * Cannot be controlled by the server.
@@ -1403,7 +1410,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @Override
 +    @ApiStatus.NonExtendable
-+    default @NotNull Collection<String> getExamples() {
++    default Collection<String> getExamples() {
 +        return this.getNativeType().getExamples();
 +    }
 +
@@ -1416,7 +1423,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <S> context type
 +     */
 +    @Override
-+    default <S> @NotNull CompletableFuture<Suggestions> listSuggestions(final @NotNull CommandContext<S> context, final @NotNull SuggestionsBuilder builder) {
++    default <S> CompletableFuture<Suggestions> listSuggestions(final CommandContext<S> context, final SuggestionsBuilder builder) {
 +        return ArgumentType.super.listSuggestions(context, builder);
 +    }
 +
@@ -1436,7 +1443,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +        @ApiStatus.NonExtendable
 +        @Override
-+        default @NotNull T parse(final @NotNull StringReader reader) throws CommandSyntaxException {
++        default T parse(final StringReader reader) throws CommandSyntaxException {
 +            return this.convert(this.getNativeType().parse(reader));
 +        }
 +
@@ -1447,7 +1454,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @return converted value
 +         * @throws CommandSyntaxException if an exception occurs while parsing
 +         */
-+        @NotNull T convert(@NotNull N nativeType) throws CommandSyntaxException;
++        T convert(N nativeType) throws CommandSyntaxException;
 +    }
 +}
 diff --git a/src/main/java/io/papermc/paper/command/brigadier/argument/RegistryArgumentExtractor.java b/src/main/java/io/papermc/paper/command/brigadier/argument/RegistryArgumentExtractor.java
@@ -1461,11 +1468,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import com.mojang.brigadier.context.CommandContext;
 +import io.papermc.paper.registry.RegistryKey;
 +import io.papermc.paper.registry.TypedKey;
-+import org.checkerframework.checker.nullness.qual.NonNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Utilities for extracting registry-related arguments from a {@link CommandContext}.
 + */
++@NullMarked
 +public final class RegistryArgumentExtractor {
 +
 +    /**
@@ -1480,7 +1488,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @throws IllegalArgumentException if the registry key doesn't match the typed key
 +     */
 +    @SuppressWarnings("unchecked")
-+    public static <T, S> @NonNull TypedKey<T> getTypedKey(final @NonNull CommandContext<S> context, final @NonNull RegistryKey<T> registryKey, final @NonNull String name) {
++    public static <T, S> TypedKey<T> getTypedKey(final CommandContext<S> context, final RegistryKey<T> registryKey, final String name) {
 +        final TypedKey<T> typedKey = context.getArgument(name, TypedKey.class);
 +        if (typedKey.registryKey().equals(registryKey)) {
 +            return typedKey;
@@ -1505,7 +1513,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.concurrent.CompletableFuture;
 +import net.kyori.adventure.chat.SignedMessage;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A resolver for a {@link SignedMessage}
@@ -1513,6 +1521,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see ArgumentTypes#signedMessage()
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface SignedMessageResolver {
 +
@@ -1521,7 +1530,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return string content
 +     */
-+    @NotNull String content();
++    String content();
 +
 +    /**
 +     * Resolves this signed message. This will the {@link CommandContext}
@@ -1535,7 +1544,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a completable future for the {@link SignedMessage}
 +     * @throws CommandSyntaxException syntax exception
 +     */
-+    @NotNull CompletableFuture<SignedMessage> resolveSignedMessage(@NotNull String argumentName, @NotNull CommandContext<CommandSourceStack> context) throws CommandSyntaxException;
++    CompletableFuture<SignedMessage> resolveSignedMessage(String argumentName, CommandContext<CommandSourceStack> context) throws CommandSyntaxException;
 +
 +}
 diff --git a/src/main/java/io/papermc/paper/command/brigadier/argument/VanillaArgumentProvider.java b/src/main/java/io/papermc/paper/command/brigadier/argument/VanillaArgumentProvider.java
@@ -1575,12 +1584,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.inventory.ItemStack;
 +import org.bukkit.scoreboard.Criteria;
 +import org.bukkit.scoreboard.DisplaySlot;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.framework.qual.DefaultQualifier;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
-+@DefaultQualifier(NonNull.class)
++@NullMarked
 +interface VanillaArgumentProvider {
 +
 +    Optional<VanillaArgumentProvider> PROVIDER = ServiceLoader.load(VanillaArgumentProvider.class)
@@ -1722,7 +1730,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import com.google.common.collect.Range;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A provider for a range of numbers
@@ -1731,13 +1739,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see io.papermc.paper.command.brigadier.argument.ArgumentTypes
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public sealed interface RangeProvider<T extends Comparable<?>> permits DoubleRangeProvider, IntegerRangeProvider {
 +
 +    /**
 +     * Provides the given range.
 +     * @return range
 +     */
-+    @NotNull
 +    Range<T> range();
 +}
 diff --git a/src/main/java/io/papermc/paper/command/brigadier/argument/resolvers/ArgumentResolver.java b/src/main/java/io/papermc/paper/command/brigadier/argument/resolvers/ArgumentResolver.java
@@ -1751,7 +1759,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import com.mojang.brigadier.exceptions.CommandSyntaxException;
 +import io.papermc.paper.command.brigadier.CommandSourceStack;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * An {@link ArgumentResolver} is capable of resolving
@@ -1761,6 +1769,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see io.papermc.paper.command.brigadier.argument.ArgumentTypes
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface ArgumentResolver<T> {
 +
@@ -1770,7 +1779,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param sourceStack source stack
 +     * @return resolved
 +     */
-+    @NotNull T resolve(@NotNull CommandSourceStack sourceStack) throws CommandSyntaxException;
++    T resolve(CommandSourceStack sourceStack) throws CommandSyntaxException;
 +}
 diff --git a/src/main/java/io/papermc/paper/command/brigadier/argument/resolvers/BlockPositionResolver.java b/src/main/java/io/papermc/paper/command/brigadier/argument/resolvers/BlockPositionResolver.java
 new file mode 100644
@@ -1928,9 +1937,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.registrar.ReloadableRegistrarEvent;
  import org.bukkit.plugin.Plugin;
  import org.jetbrains.annotations.ApiStatus;
- 
+ import org.jspecify.annotations.NullMarked;
-@@ -0,0 +0,0 @@ import org.jetbrains.annotations.ApiStatus;
+@@ -0,0 +0,0 @@ import org.jspecify.annotations.NullMarked;
- @ApiStatus.Experimental
+ @NullMarked
  public final class LifecycleEvents {
  
 +    /**

patches/api/Bucketable-API.patch

@@ -15,11 +15,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.Sound;
 +import org.bukkit.entity.Entity;
 +import org.bukkit.inventory.ItemStack;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents an entity that can be bucketed.
 + */
++@NullMarked
 +public interface Bucketable extends Entity {
 +
 +    /**
@@ -41,7 +42,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return bucket form
 +     */
-+    @NotNull
 +    ItemStack getBaseBucketItem();
 +
 +    /**
@@ -49,7 +49,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * is picked up in a bucket.
 +     * @return bucket pickup sound
 +     */
-+    @NotNull
 +    Sound getPickupSound();
 +}
 diff --git a/src/main/java/org/bukkit/entity/Axolotl.java b/src/main/java/org/bukkit/entity/Axolotl.java

patches/api/Code-Generation.patch

@@ -121,6 +121,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.potion.PotionEffectType;
 +import org.bukkit.potion.PotionType;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +import static io.papermc.paper.registry.RegistryKeyImpl.create;
 +
@@ -137,6 +138,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <T> the value type
 + */
 +@SuppressWarnings("unused")
++@NullMarked
 +public sealed interface RegistryKey<T> extends Keyed permits RegistryKeyImpl {
 +
 +    /* ******************* *
@@ -278,9 +280,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Set;
 +import net.kyori.adventure.key.Key;
 +import org.intellij.lang.annotations.Subst;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
-+record RegistryKeyImpl<T>(@NotNull Key key) implements RegistryKey<T> {
++@NullMarked
++record RegistryKeyImpl<T>(Key key) implements RegistryKey<T> {
 +
 +    static final Set<RegistryKey<?>> REGISTRY_KEYS = Sets.newIdentityHashSet();
 +
@@ -307,7 +311,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import net.kyori.adventure.key.Key;
 +import net.kyori.adventure.key.Keyed;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents a key for a value in a specific registry.
@@ -315,6 +319,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <T> the value type for the registry
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public sealed interface TypedKey<T> extends Keyed permits TypedKeyImpl {
 +
 +    /**
@@ -323,7 +328,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the value's key
 +     */
 +    @Override
-+    @NotNull Key key();
++    Key key();
 +
 +    /**
 +     * Gets the registry key for the value this key
@@ -331,7 +336,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the registry key
 +     */
-+    @NotNull RegistryKey<T> registryKey();
++    RegistryKey<T> registryKey();
 +
 +    /**
 +     * Create a typed key from a key and a registry key.
@@ -342,7 +347,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new key for the value key and registry key
 +     */
 +    @ApiStatus.Experimental
-+    static <T> @NotNull TypedKey<T> create(final @NotNull RegistryKey<T> registryKey, final @NotNull Key key) {
++    static <T> TypedKey<T> create(final RegistryKey<T> registryKey, final Key key) {
 +        return new TypedKeyImpl<>(key, registryKey);
 +    }
 +}
@@ -355,10 +360,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.registry;
 +
 +import net.kyori.adventure.key.Key;
-+import net.kyori.adventure.key.Keyed;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.NotNull;
 +
-+record TypedKeyImpl<T>(@NotNull Key key, @NotNull RegistryKey<T> registryKey) implements TypedKey<T> {
++@NullMarked
++record TypedKeyImpl<T>(Key key, RegistryKey<T> registryKey) implements TypedKey<T> {
 +}
 diff --git a/src/main/java/org/bukkit/MinecraftExperimental.java b/src/main/java/org/bukkit/MinecraftExperimental.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644

patches/api/Custom-Potion-Mixes.patch

@@ -12,22 +12,20 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.potion;
 +
++import java.util.Objects;
 +import java.util.function.Predicate;
 +import org.bukkit.Keyed;
 +import org.bukkit.NamespacedKey;
 +import org.bukkit.inventory.ItemStack;
 +import org.bukkit.inventory.RecipeChoice;
-+import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+
-+import java.util.Objects;
 +
 +/**
 + * Represents a potion mix made in a Brewing Stand.
 + */
-+@ApiStatus.NonExtendable
++@NullMarked
-+public class PotionMix implements Keyed {
++public final class PotionMix implements Keyed {
 +
 +    private final NamespacedKey key;
 +    private final ItemStack result;
@@ -42,7 +40,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param input the input placed into the bottom 3 slots
 +     * @param ingredient the ingredient placed into the top slot
 +     */
-+    public PotionMix(final @NotNull NamespacedKey key, final @NotNull ItemStack result, final @NotNull RecipeChoice input, final @NotNull RecipeChoice ingredient) {
++    public PotionMix(final NamespacedKey key, final ItemStack result, final RecipeChoice input, final RecipeChoice ingredient) {
 +        this.key = key;
 +        this.result = result;
 +        this.input = input;
@@ -57,12 +55,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new RecipeChoice
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    public static @NotNull RecipeChoice createPredicateChoice(final @NotNull Predicate<? super ItemStack> stackPredicate) {
++    public static RecipeChoice createPredicateChoice(final Predicate<? super ItemStack> stackPredicate) {
 +        return new PredicateRecipeChoice(stackPredicate);
 +    }
 +
 +    @Override
-+    public @NotNull NamespacedKey getKey() {
++    public NamespacedKey getKey() {
 +        return this.key;
 +    }
 +
@@ -71,7 +69,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the result itemstack
 +     */
-+    public @NotNull ItemStack getResult() {
++    public ItemStack getResult() {
 +        return this.result;
 +    }
 +
@@ -80,7 +78,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the bottom 3 slot ingredients
 +     */
-+    public @NotNull RecipeChoice getInput() {
++    public RecipeChoice getInput() {
 +        return this.input;
 +    }
 +
@@ -89,7 +87,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the top slot input
 +     */
-+    public @NotNull RecipeChoice getIngredient() {
++    public RecipeChoice getIngredient() {
 +        return this.ingredient;
 +    }
 +
@@ -126,12 +124,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.function.Predicate;
 +import org.bukkit.inventory.ItemStack;
 +import org.bukkit.inventory.RecipeChoice;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.framework.qual.DefaultQualifier;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
-+@DefaultQualifier(NonNull.class)
++@NullMarked
 +record PredicateRecipeChoice(Predicate<? super ItemStack> itemStackPredicate) implements RecipeChoice, Cloneable {
 +
 +    @Override

patches/api/Expand-ArmorStand-API.patch

@@ -18,12 +18,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.math;
 +
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Rotations is an immutable object that stores rotations
 + * in degrees on each axis (X, Y, Z).
 + */
++@NullMarked
 +public interface Rotations {
 +
 +    /**
@@ -39,7 +40,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param z the angle for the Z axis in degrees
 +     * @return Rotations instance holding the provided rotations
 +     */
-+    static @NotNull Rotations ofDegrees(double x, double y, double z) {
++    static Rotations ofDegrees(final double x, final double y, final double z) {
 +        return new RotationsImpl(x, y, z);
 +    }
 +
@@ -71,7 +72,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param x the angle in degrees
 +     * @return the resultant Rotations
 +     */
-+    @NotNull Rotations withX(double x);
++    Rotations withX(double x);
 +
 +    /**
 +     * Returns a new Rotations instance which is the result
@@ -80,7 +81,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param y the angle in degrees
 +     * @return the resultant Rotations
 +     */
-+    @NotNull Rotations withY(double y);
++    Rotations withY(double y);
 +
 +    /**
 +     * Returns a new Rotations instance which is the result
@@ -89,7 +90,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param z the angle in degrees
 +     * @return the resultant Rotations
 +     */
-+    @NotNull Rotations withZ(double z);
++    Rotations withZ(double z);
 +
 +    /**
 +     * Returns a new Rotations instance which is the result of adding
@@ -100,7 +101,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param z the angle to add to the Z axis in degrees
 +     * @return the resultant Rotations
 +     */
-+    @NotNull Rotations add(double x, double y, double z);
++    Rotations add(double x, double y, double z);
 +
 +    /**
 +     * Returns a new Rotations instance which is the result of subtracting
@@ -111,8 +112,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param z the angle to subtract from the Z axis in degrees
 +     * @return the resultant Rotations
 +     */
-+    default @NotNull Rotations subtract(double x, double y, double z) {
++    default Rotations subtract(final double x, final double y, final double z) {
-+        return add(-x, -y, -z);
++        return this.add(-x, -y, -z);
 +    }
 +
 +}
@@ -124,27 +125,28 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.math;
 +
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
++@NullMarked
 +record RotationsImpl(double x, double y, double z) implements Rotations {
 +
 +    @Override
-+    public @NotNull RotationsImpl withX(double x) {
++    public RotationsImpl withX(final double x) {
-+        return new RotationsImpl(x, y, z);
++        return new RotationsImpl(x, this.y, this.z);
 +    }
 +
 +    @Override
-+    public @NotNull RotationsImpl withY(double y) {
++    public RotationsImpl withY(final double y) {
-+        return new RotationsImpl(x, y, z);
++        return new RotationsImpl(this.x, y, this.z);
 +    }
 +
 +    @Override
-+    public @NotNull RotationsImpl withZ(double z) {
++    public RotationsImpl withZ(final double z) {
-+        return new RotationsImpl(x, y, z);
++        return new RotationsImpl(this.x, this.y, z);
 +    }
 +
 +    @Override
-+    public @NotNull RotationsImpl add(double x, double y, double z) {
++    public RotationsImpl add(final double x, final double y, final double z) {
 +        return new RotationsImpl(this.x + x, this.y + y, this.z + z);
 +    }
 +

patches/api/Expose-server-build-information.patch

@@ -75,11 +75,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import net.kyori.adventure.key.Key;
 +import net.kyori.adventure.util.Services;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Information about the current server build.
 + */
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface ServerBuildInfo {
 +    /**
@@ -92,7 +93,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the {@code ServerBuildInfo}
 +     */
-+    static @NotNull ServerBuildInfo buildInfo() {
++    static ServerBuildInfo buildInfo() {
 +        //<editor-fold defaultstate="collapsed" desc="Holder">
 +        final class Holder {
 +            static final Optional<ServerBuildInfo> INSTANCE = Services.service(ServerBuildInfo.class);
@@ -106,7 +107,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the brand id of the server (e.g. "papermc:paper")
 +     */
-+    @NotNull Key brandId();
++    Key brandId();
 +
 +    /**
 +     * Checks if the current server supports the specified brand.
@@ -115,56 +116,56 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return {@code true} if the server supports the specified brand
 +     */
 +    @ApiStatus.Experimental
-+    boolean isBrandCompatible(final @NotNull Key brandId);
++    boolean isBrandCompatible(final Key brandId);
 +
 +    /**
 +     * Gets the brand name of the server.
 +     *
 +     * @return the brand name of the server (e.g. "Paper")
 +     */
-+    @NotNull String brandName();
++    String brandName();
 +
 +    /**
 +     * Gets the Minecraft version id.
 +     *
 +     * @return the Minecraft version id (e.g. "1.20.4", "1.20.2-pre2", "23w31a")
 +     */
-+    @NotNull String minecraftVersionId();
++    String minecraftVersionId();
 +
 +    /**
 +     * Gets the Minecraft version name.
 +     *
 +     * @return the Minecraft version name (e.g. "1.20.4", "1.20.2 Pre-release 2", "23w31a")
 +     */
-+    @NotNull String minecraftVersionName();
++    String minecraftVersionName();
 +
 +    /**
 +     * Gets the build number.
 +     *
 +     * @return the build number
 +     */
-+    @NotNull OptionalInt buildNumber();
++    OptionalInt buildNumber();
 +
 +    /**
 +     * Gets the build time.
 +     *
 +     * @return the build time
 +     */
-+    @NotNull Instant buildTime();
++    Instant buildTime();
 +
 +    /**
 +     * Gets the git commit branch.
 +     *
 +     * @return the git commit branch
 +     */
-+    @NotNull Optional<String> gitBranch();
++    Optional<String> gitBranch();
 +
 +    /**
 +     * Gets the git commit hash.
 +     *
 +     * @return the git commit hash
 +     */
-+    @NotNull Optional<String> gitCommit();
++    Optional<String> gitCommit();
 +
 +    /**
 +     * Creates a string representation of the server build information.
@@ -172,7 +173,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param representation the type of representation
 +     * @return a string
 +     */
-+    @NotNull String asString(final @NotNull StringRepresentation representation);
++    String asString(final StringRepresentation representation);
 +
 +    /**
 +     * String representation types.
@@ -204,9 +205,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.WeakHashMap;
 +import java.util.jar.Manifest;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
++@NullMarked
 +@ApiStatus.Internal
 +public final class JarManifests {
 +    private JarManifests() {
@@ -214,7 +216,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +    private static final Map<ClassLoader, Manifest> MANIFESTS = Collections.synchronizedMap(new WeakHashMap<>());
 +
-+    public static @Nullable Manifest manifest(final @NotNull Class<?> clazz) {
++    public static @Nullable Manifest manifest(final Class<?> clazz) {
 +        return MANIFESTS.computeIfAbsent(clazz.getClassLoader(), classLoader -> {
 +            final String classLocation = "/" + clazz.getName().replace(".", "/") + ".class";
 +            final URL resource = clazz.getResource(classLocation);

patches/api/Fix-issues-with-recipe-API.patch

@@ -63,12 +63,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package org.bukkit.inventory;
 +
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.framework.qual.DefaultQualifier;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
-+@DefaultQualifier(NonNull.class)
++@NullMarked
 +record EmptyRecipeChoice() implements RecipeChoice {
 +
 +    static final RecipeChoice INSTANCE = new EmptyRecipeChoice();

patches/api/Friction-API.patch

@@ -14,11 +14,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import net.kyori.adventure.util.TriState;
 +import org.bukkit.entity.Entity;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents an {@link Entity} that can experience friction with the air and ground.
 + */
++@NullMarked
 +public interface Frictional {
 +
 +    /**
@@ -29,7 +30,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the entity's friction state
 +     */
-+    @NotNull
 +    TriState getFrictionState();
 +
 +    /**
@@ -42,7 +42,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param state the new friction state to set for the entity
 +     */
-+    void setFrictionState(@NotNull TriState state);
++    void setFrictionState(TriState state);
 +
 +}
 diff --git a/src/main/java/org/bukkit/entity/Item.java b/src/main/java/org/bukkit/entity/Item.java

patches/api/Improve-the-Saddle-API-for-Horses.patch

@@ -14,8 +14,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package org.bukkit.inventory;
 +
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
++@NullMarked
 +public interface ArmoredHorseInventory extends AbstractHorseInventory {
 +
 +    /**
@@ -23,8 +25,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the armor item
 +     */
-+    @Nullable
++    @Nullable ItemStack getArmor();
-+    ItemStack getArmor();
 +
 +    /**
 +     * Sets the item in the horse's armor slot.
@@ -80,4 +81,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package org.bukkit.inventory;
 +
-+public interface SaddledHorseInventory extends AbstractHorseInventory {}
++import org.jspecify.annotations.NullMarked;
++
++@NullMarked
++public interface SaddledHorseInventory extends AbstractHorseInventory {
++}

patches/api/Introduce-registry-entry-and-builders.patch

@@ -40,18 +40,18 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.enchantments.Enchantment;
 +import org.bukkit.inventory.EquipmentSlotGroup;
 +import org.bukkit.inventory.ItemType;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.checker.nullness.qual.Nullable;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
 +import org.jetbrains.annotations.Range;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * A data-centric version-specific registry entry for the {@link Enchantment} type.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface EnchantmentRegistryEntry {
 +
@@ -61,14 +61,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the description component.
 +     */
-+    @NonNull Component description();
++    Component description();
 +
 +    /**
 +     * Provides the registry key set referencing the items this enchantment is supported on.
 +     *
 +     * @return the registry key set.
 +     */
-+    @NonNull RegistryKeySet<ItemType> supportedItems();
++    RegistryKeySet<ItemType> supportedItems();
 +
 +    /**
 +     * Provides the registry key set referencing the item types this enchantment can be applied to when
@@ -106,7 +106,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see <a href="https://minecraft.wiki/w/Enchanting/Levels">https://minecraft.wiki/w/Enchanting/Levels</a> for
 +     * examplary costs.
 +     */
-+    @NonNull EnchantmentCost minimumCost();
++    EnchantmentCost minimumCost();
 +
 +    /**
 +     * Provides the maximum cost allowed to enchant an item with this enchantment.
@@ -117,7 +117,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see <a href="https://minecraft.wiki/w/Enchanting/Levels">https://minecraft.wiki/w/Enchanting/Levels</a> for
 +     * examplary costs.
 +     */
-+    @NonNull EnchantmentCost maximumCost();
++    EnchantmentCost maximumCost();
 +
 +    /**
 +     * Provides the cost of applying this enchantment using an anvil.
@@ -140,7 +140,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a list of equipment slot groups.
 +     * @see Enchantment#getActiveSlotGroups()
 +     */
-+    @NonNull @Unmodifiable List<EquipmentSlotGroup> activeSlots();
++    @Unmodifiable List<EquipmentSlotGroup> activeSlots();
 +
 +    /**
 +     * Provides the registry key set of enchantments that this enchantment is exclusive with.
@@ -150,7 +150,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return a registry set of enchantments exclusive to this one.
 +     */
-+    @NonNull RegistryKeySet<Enchantment> exclusiveWith();
++    RegistryKeySet<Enchantment> exclusiveWith();
 +
 +    /**
 +     * A mutable builder for the {@link EnchantmentRegistryEntry} plugins may change in applicable registry events.
@@ -179,7 +179,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @return this builder.
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder description(@NonNull Component description);
++        Builder description(Component description);
 +
 +        /**
 +         * Configures the set of supported items this enchantment can be applied on. This
@@ -195,7 +195,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @see io.papermc.paper.registry.event.RegistryFreezeEvent#getOrCreateTag(TagKey)
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder supportedItems(@NonNull RegistryKeySet<ItemType> supportedItems);
++        Builder supportedItems(RegistryKeySet<ItemType> supportedItems);
 +
 +        /**
 +         * Configures a set of item types this enchantment can naturally be applied to, when enchanting in an
@@ -216,7 +216,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @see io.papermc.paper.registry.event.RegistryFreezeEvent#getOrCreateTag(TagKey)
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder primaryItems(@Nullable RegistryKeySet<ItemType> primaryItems);
++        Builder primaryItems(@Nullable RegistryKeySet<ItemType> primaryItems);
 +
 +        /**
 +         * Configures the weight of this enchantment used by the weighted random when selecting enchantments.
@@ -226,7 +226,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @see <a href="https://minecraft.wiki/w/Enchanting">https://minecraft.wiki/w/Enchanting</a> for examplary weights.
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder weight(@Range(from = 1, to = 1024) int weight);
++        Builder weight(@Range(from = 1, to = 1024) int weight);
 +
 +        /**
 +         * Configures the maximum level this enchantment can have when applied.
@@ -235,7 +235,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @return this builder.
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder maxLevel(@Range(from = 1, to = 255) int maxLevel);
++        Builder maxLevel(@Range(from = 1, to = 255) int maxLevel);
 +
 +        /**
 +         * Configures the minimum cost needed to enchant an item with this enchantment.
@@ -248,7 +248,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * examplary costs.
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder minimumCost(@NotNull EnchantmentCost minimumCost);
++        Builder minimumCost(EnchantmentCost minimumCost);
 +
 +        /**
 +         * Configures the maximum cost to enchant an item with this enchantment.
@@ -261,7 +261,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * examplary costs.
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder maximumCost(@NotNull EnchantmentCost maximumCost);
++        Builder maximumCost(EnchantmentCost maximumCost);
 +
 +        /**
 +         * Configures the cost of applying this enchantment using an anvil.
@@ -275,7 +275,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @see Enchantment#getAnvilCost()
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder anvilCost(@Range(from = 0, to = Integer.MAX_VALUE) int anvilCost);
++        Builder anvilCost(@Range(from = 0, to = Integer.MAX_VALUE) int anvilCost);
 +
 +        /**
 +         * Configures the list of slot groups this enchantment may be active in.
@@ -288,7 +288,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @see Enchantment#getActiveSlotGroups()
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        default @NonNull Builder activeSlots(final @NonNull EquipmentSlotGroup @NonNull... activeSlots) {
++        default Builder activeSlots(final EquipmentSlotGroup... activeSlots) {
 +            return this.activeSlots(List.of(activeSlots));
 +        }
 +
@@ -303,7 +303,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @see Enchantment#getActiveSlotGroups()
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder activeSlots(@NonNull Iterable<@NonNull EquipmentSlotGroup> activeSlots);
++        Builder activeSlots(Iterable<EquipmentSlotGroup> activeSlots);
 +
 +        /**
 +         * Configures the registry key set of enchantments that this enchantment is exclusive with.
@@ -319,7 +319,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @see io.papermc.paper.registry.event.RegistryFreezeEvent#getOrCreateTag(TagKey)
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder exclusiveWith(@NonNull RegistryKeySet<Enchantment> exclusiveWith);
++        Builder exclusiveWith(RegistryKeySet<Enchantment> exclusiveWith);
 +    }
 +
 +    /**
@@ -369,15 +369,16 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import io.papermc.paper.registry.RegistryBuilder;
 +import org.bukkit.GameEvent;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
 +import org.jetbrains.annotations.Range;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A data-centric version-specific registry entry for the {@link GameEvent} type.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface GameEventRegistryEntry {
 +
@@ -410,7 +411,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +         * @see GameEvent#getRange()
 +         */
 +        @Contract(value = "_ -> this", mutates = "this")
-+        @NonNull Builder range(@Range(from = 0, to = Integer.MAX_VALUE) int range);
++        Builder range(@Range(from = 0, to = Integer.MAX_VALUE) int range);
 +    }
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/data/package-info.java b/src/main/java/io/papermc/paper/registry/data/package-info.java
@@ -441,14 +442,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.GameEvent;
 +import org.bukkit.enchantments.Enchantment;
  import org.jetbrains.annotations.ApiStatus;
+ import org.jspecify.annotations.NullMarked;
  
 +import static io.papermc.paper.registry.event.RegistryEventProviderImpl.create;
 +
  /**
   * Holds providers for {@link RegistryEntryAddEvent} and {@link RegistryFreezeEvent}
   * handlers for each applicable registry.
-@@ -0,0 +0,0 @@ import org.jetbrains.annotations.ApiStatus;
+@@ -0,0 +0,0 @@ import org.jspecify.annotations.NullMarked;
- @ApiStatus.Experimental
+ @NullMarked
  public final class RegistryEvents {
  
 +    public static final RegistryEventProvider<GameEvent, GameEventRegistryEntry.Builder> GAME_EVENT = create(RegistryKey.GAME_EVENT);

patches/api/ItemStack-Tooltip-API.patch

@@ -14,12 +14,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import org.bukkit.entity.Player;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Context for computing itemstack tooltips via
 + * {@link org.bukkit.inventory.ItemStack#computeTooltipLines(TooltipContext, Player)}
 + */
++@NullMarked
 +public interface TooltipContext {
 +
 +    /**
@@ -31,7 +32,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new context
 +     */
 +    @Contract("_, _ -> new")
-+    static @NotNull TooltipContext create(final boolean advanced, final boolean creative) {
++    static TooltipContext create(final boolean advanced, final boolean creative) {
 +        return new TooltipContextImpl(advanced, creative);
 +    }
 +
@@ -41,7 +42,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new context
 +     */
 +    @Contract("-> new")
-+    static @NotNull TooltipContext create() {
++    static TooltipContext create() {
 +        return new TooltipContextImpl(false, false);
 +    }
 +
@@ -74,7 +75,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new context
 +     */
 +    @Contract("-> new")
-+    @NotNull TooltipContext asAdvanced();
++    TooltipContext asAdvanced();
 +
 +    /**
 +     * Returns a new context with {@link #isCreative()}
@@ -83,7 +84,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a new context
 +     */
 +    @Contract("-> new")
-+    @NotNull TooltipContext asCreative();
++    TooltipContext asCreative();
 +}
 diff --git a/src/main/java/io/papermc/paper/inventory/tooltip/TooltipContextImpl.java b/src/main/java/io/papermc/paper/inventory/tooltip/TooltipContextImpl.java
 new file mode 100644
@@ -93,17 +94,18 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.inventory.tooltip;
 +
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
++@NullMarked
 +record TooltipContextImpl(boolean isAdvanced, boolean isCreative) implements TooltipContext {
 +
 +    @Override
-+    public @NotNull TooltipContext asCreative() {
++    public TooltipContext asCreative() {
 +        return new TooltipContextImpl(this.isAdvanced, true);
 +    }
 +
 +    @Override
-+    public @NotNull TooltipContext asAdvanced() {
++    public TooltipContext asAdvanced() {
 +        return new TooltipContextImpl(true, this.isCreative);
 +    }
 +}

patches/api/Leashable-API.patch

@@ -13,12 +13,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.entity;
 +
 +import org.bukkit.entity.Entity;
-+import org.checkerframework.checker.nullness.qual.NonNull;
++import org.jspecify.annotations.NullMarked;
-+import org.checkerframework.checker.nullness.qual.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Represents an entity that can be leashed.
 + */
++@NullMarked
 +public interface Leashable extends Entity {
 +
 +    /**
@@ -34,7 +35,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the entity holding the leash
 +     * @throws IllegalStateException if not currently leashed
 +     */
-+    @NonNull Entity getLeashHolder() throws IllegalStateException;
++    Entity getLeashHolder() throws IllegalStateException;
 +
 +    /**
 +     * Sets the leash on this entity to be held by the supplied entity.

patches/api/LootTable-API.patch

@@ -19,7 +19,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package com.destroystokyo.paper.loottable;
 +
 +import org.bukkit.block.Block;
-+import org.jetbrains.annotations.NotNull;
 +import org.jspecify.annotations.NullMarked;
 +
 +/**
@@ -43,7 +42,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package com.destroystokyo.paper.loottable;
 +
 +import org.bukkit.entity.Entity;
-+import org.jetbrains.annotations.NotNull;
 +import org.jspecify.annotations.NullMarked;
 +
 +/**
@@ -69,8 +67,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.UUID;
 +import org.bukkit.entity.Player;
 +import org.bukkit.loot.Lootable;
-+import org.jetbrains.annotations.Nullable;
 +import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Represents an Inventory that contains a Loot Table associated to it that will
@@ -141,8 +139,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param player The player to check
 +     * @return Timestamp last looted, or null if player has not looted this object
 +     */
-+    @Nullable
++    @Nullable Long getLastLooted(UUID player);
-+    Long getLastLooted(UUID player);
 +
 +    /**
 +     * Change the state of whether a player has looted this block

patches/api/Make-a-PDC-view-accessible-directly-from-ItemStack.patch

@@ -18,15 +18,17 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.persistence.PersistentDataContainer;
 +import org.bukkit.persistence.PersistentDataHolder;
 +import org.bukkit.persistence.PersistentDataType;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.checker.nullness.qual.Nullable;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * This represents a view of a persistent data container. No
 + * methods on this interface mutate the container.
++ *
 + * @see PersistentDataContainer
 + */
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface PersistentDataContainerView {
 +
@@ -52,14 +54,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param type the type the primative stored value has to match
 +     * @param <P> the generic type of the stored primitive
 +     * @param <C> the generic type of the eventually created complex object
-+     *
 +     * @return if a value with the provided key and type exists
-+     *
 +     * @throws IllegalArgumentException if the key to look up is null
 +     * @throws IllegalArgumentException if the type to cast the found object to is
 +     * null
 +     */
-+    <P, C> boolean has(@NonNull NamespacedKey key, @NonNull PersistentDataType<P, C> type);
++    <P, C> boolean has(NamespacedKey key, PersistentDataType<P, C> type);
 +
 +    /**
 +     * Returns if the persistent metadata provider has metadata registered matching
@@ -73,12 +73,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * namespace.
 +     *
 +     * @param key the key the value is stored under
-+     *
 +     * @return if a value with the provided key exists
-+     *
 +     * @throws IllegalArgumentException if the key to look up is null
 +     */
-+    boolean has(@NonNull NamespacedKey key);
++    boolean has(NamespacedKey key);
 +
 +    /**
 +     * Returns the metadata value that is stored on the
@@ -88,10 +86,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param type the type the value must have and will be casted to
 +     * @param <P> the generic type of the stored primitive
 +     * @param <C> the generic type of the eventually created complex object
-+     *
 +     * @return the value or {@code null} if no value was mapped under the given
 +     * value
-+     *
 +     * @throws IllegalArgumentException if the key to look up is null
 +     * @throws IllegalArgumentException if the type to cast the found object to is
 +     * null
@@ -101,7 +97,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * the {@link
 +     * PersistentDataType#getPrimitiveType()}
 +     */
-+    <P, C> @Nullable C get(@NonNull NamespacedKey key, @NonNull PersistentDataType<P, C> type);
++    <P, C> @Nullable C get(NamespacedKey key, PersistentDataType<P, C> type);
 +
 +    /**
 +     * Returns the metadata value that is stored on the
@@ -114,10 +110,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * the provided key
 +     * @param <P> the generic type of the stored primitive
 +     * @param <C> the generic type of the eventually created complex object
-+     *
 +     * @return the value or the default value if no value was mapped under the
 +     * given key
-+     *
 +     * @throws IllegalArgumentException if the key to look up is null
 +     * @throws IllegalArgumentException if the type to cast the found object to is
 +     * null
@@ -126,18 +120,18 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @throws IllegalArgumentException if no suitable adapter was found for
 +     * the {@link PersistentDataType#getPrimitiveType()}
 +     */
-+    <P, C> @NonNull C getOrDefault(@NonNull NamespacedKey key, @NonNull PersistentDataType<P, C> type, @NonNull C defaultValue);
++    <P, C> C getOrDefault(NamespacedKey key, PersistentDataType<P, C> type, C defaultValue);
 +
 +    /**
 +     * Get the set of keys present on this {@link PersistentDataContainer}
 +     * instance.
-+     *
++     * <p>
 +     * Any changes made to the returned set will not be reflected on the
 +     * instance.
 +     *
 +     * @return the key set
 +     */
-+    @NonNull Set<NamespacedKey> getKeys();
++    Set<NamespacedKey> getKeys();
 +
 +    /**
 +     * Returns if the container instance is empty, therefore has no entries
@@ -156,17 +150,16 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param other the container to copy to
 +     * @param replace whether to replace any matching values in the target container
-+     *
 +     * @throws IllegalArgumentException if the other container is null
 +     */
-+    void copyTo(@NonNull PersistentDataContainer other, boolean replace);
++    void copyTo(PersistentDataContainer other, boolean replace);
 +
 +    /**
 +     * Returns the adapter context this tag container uses.
 +     *
 +     * @return the tag context
 +     */
-+    @NonNull PersistentDataAdapterContext getAdapterContext();
++    PersistentDataAdapterContext getAdapterContext();
 +
 +    /**
 +     * Serialize this {@link PersistentDataContainer} instance to a
@@ -175,7 +168,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a binary representation of this container
 +     * @throws java.io.IOException if we fail to write this container to a byte array
 +     */
-+    byte @NonNull [] serializeToBytes() throws java.io.IOException;
++    byte[] serializeToBytes() throws java.io.IOException;
 +}
 diff --git a/src/main/java/io/papermc/paper/persistence/PersistentDataViewHolder.java b/src/main/java/io/papermc/paper/persistence/PersistentDataViewHolder.java
 new file mode 100644
@@ -185,13 +178,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.persistence;
 +
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * The {@link PersistentDataViewHolder} interface defines an object that can view
 + * custom persistent data on it.
 + */
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface PersistentDataViewHolder {
 +
@@ -204,7 +198,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the persistent data container view
 +     */
-+    @NonNull PersistentDataContainerView getPersistentDataContainer();
++    PersistentDataContainerView getPersistentDataContainer();
 +}
 diff --git a/src/main/java/org/bukkit/inventory/ItemStack.java b/src/main/java/org/bukkit/inventory/ItemStack.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644

patches/api/Misc-Utils.patch

@@ -14,33 +14,36 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import java.util.concurrent.ConcurrentLinkedQueue;
 +import java.util.concurrent.atomic.LongAdder;
-+import org.jetbrains.annotations.NotNull;
++import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
++@NullMarked
++@ApiStatus.Internal
 +public class CachedSizeConcurrentLinkedQueue<E> extends ConcurrentLinkedQueue<E> {
++
 +    private final LongAdder cachedSize = new LongAdder();
 +
 +    @Override
-+    public boolean add(@NotNull E e) {
++    public boolean add(final E e) {
-+        boolean result = super.add(e);
++        final boolean result = super.add(e);
 +        if (result) {
-+            cachedSize.increment();
++            this.cachedSize.increment();
 +        }
 +        return result;
 +    }
 +
-+    @Nullable
 +    @Override
-+    public E poll() {
++    public @Nullable E poll() {
-+        E result = super.poll();
++        final E result = super.poll();
 +        if (result != null) {
-+            cachedSize.decrement();
++            this.cachedSize.decrement();
 +        }
 +        return result;
 +    }
 +
 +    @Override
 +    public int size() {
-+        return cachedSize.intValue();
++        return this.cachedSize.intValue();
 +    }
 +}

patches/api/Missing-Entity-API.patch

@@ -23,12 +23,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.entity;
 +
 +import org.bukkit.entity.Fish;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * Represents a fish that can school with other fish.
 + */
++@NullMarked
 +public interface SchoolableFish extends Fish {
 +
 +    /**
@@ -36,7 +37,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param leader fish to follow
 +     */
-+    void startFollowing(@NotNull SchoolableFish leader);
++    void startFollowing(SchoolableFish leader);
 +
 +    /**
 +     * Causes the fish to stop following their current
@@ -63,8 +64,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return following fish
 +     */
-+    @Nullable
++    @Nullable SchoolableFish getSchoolLeader();
-+    SchoolableFish getSchoolLeader();
 +
 +}
 diff --git a/src/main/java/org/bukkit/entity/AbstractHorse.java b/src/main/java/org/bukkit/entity/AbstractHorse.java

patches/api/More-CommandBlock-API.patch

@@ -13,9 +13,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.command;
 +
 +import net.kyori.adventure.text.Component;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
++@NullMarked
 +public interface CommandBlockHolder {
 +
 +    /**
@@ -25,7 +26,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return Command that this CommandBlock will run when activated.
 +     */
-+    @NotNull
 +    String getCommand();
 +
 +    /**
@@ -42,7 +42,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the last output
 +     */
-+    @NotNull
 +    Component lastOutput();
 +
 +    /**

patches/api/Paper-Plugins.patch

@@ -33,20 +33,20 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.plugin;
 +
++import java.util.List;
++import java.util.Set;
 +import org.bukkit.permissions.Permissible;
 +import org.bukkit.permissions.Permission;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
-+
-+import java.util.List;
-+import java.util.Set;
 +
 +/**
 + * A permission manager implementation to keep backwards compatibility partially alive with existing plugins that used
 + * the bukkit one before.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public interface PermissionManager {
 +
 +    /**
@@ -55,8 +55,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param name Name of the permission
 +     * @return Permission, or null if none
 +     */
-+    @Nullable
++    @Nullable Permission getPermission(String name);
-+    Permission getPermission(@NotNull String name);
 +
 +    /**
 +     * Adds a {@link Permission} to this plugin manager.
@@ -68,7 +67,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @throws IllegalArgumentException Thrown when a permission with the same
 +     *                                  name already exists
 +     */
-+    void addPermission(@NotNull Permission perm);
++    void addPermission(Permission perm);
 +
 +    /**
 +     * Removes a {@link Permission} registration from this plugin manager.
@@ -81,7 +80,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param perm Permission to remove
 +     */
-+    void removePermission(@NotNull Permission perm);
++    void removePermission(Permission perm);
 +
 +    /**
 +     * Removes a {@link Permission} registration from this plugin manager.
@@ -94,7 +93,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param name Permission to remove
 +     */
-+    void removePermission(@NotNull String name);
++    void removePermission(String name);
 +
 +    /**
 +     * Gets the default permissions for the given op status
@@ -102,7 +101,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param op Which set of default permissions to get
 +     * @return The default permissions
 +     */
-+    @NotNull
 +    Set<Permission> getDefaultPermissions(boolean op);
 +
 +    /**
@@ -113,7 +111,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param perm Permission to recalculate
 +     */
-+    void recalculatePermissionDefaults(@NotNull Permission perm);
++    void recalculatePermissionDefaults(Permission perm);
 +
 +    /**
 +     * Subscribes the given Permissible for information about the requested
@@ -125,7 +123,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param permission  Permission to subscribe to
 +     * @param permissible Permissible subscribing
 +     */
-+    void subscribeToPermission(@NotNull String permission, @NotNull Permissible permissible);
++    void subscribeToPermission(String permission, Permissible permissible);
 +
 +    /**
 +     * Unsubscribes the given Permissible for information about the requested
@@ -134,7 +132,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param permission  Permission to unsubscribe from
 +     * @param permissible Permissible subscribing
 +     */
-+    void unsubscribeFromPermission(@NotNull String permission, @NotNull Permissible permissible);
++    void unsubscribeFromPermission(String permission, Permissible permissible);
 +
 +    /**
 +     * Gets a set containing all subscribed {@link Permissible}s to the given
@@ -143,8 +141,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param permission Permission to query for
 +     * @return Set containing all subscribed permissions
 +     */
-+    @NotNull
++    Set<Permissible> getPermissionSubscriptions(String permission);
-+    Set<Permissible> getPermissionSubscriptions(@NotNull String permission);
 +
 +    /**
 +     * Subscribes to the given Default permissions by operator status
@@ -155,7 +152,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param op          Default list to subscribe to
 +     * @param permissible Permissible subscribing
 +     */
-+    void subscribeToDefaultPerms(boolean op, @NotNull Permissible permissible);
++    void subscribeToDefaultPerms(boolean op, Permissible permissible);
 +
 +    /**
 +     * Unsubscribes from the given Default permissions by operator status
@@ -163,7 +160,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param op          Default list to unsubscribe from
 +     * @param permissible Permissible subscribing
 +     */
-+    void unsubscribeFromDefaultPerms(boolean op, @NotNull Permissible permissible);
++    void unsubscribeFromDefaultPerms(boolean op, Permissible permissible);
 +
 +    /**
 +     * Gets a set containing all subscribed {@link Permissible}s to the given
@@ -172,7 +169,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param op Default list to query for
 +     * @return Set containing all subscribed permissions
 +     */
-+    @NotNull
 +    Set<Permissible> getDefaultPermSubscriptions(boolean op);
 +
 +    /**
@@ -182,7 +178,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return Set containing all current registered permissions
 +     */
-+    @NotNull
 +    Set<Permission> getPermissions();
 +
 +    /**
@@ -192,7 +187,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param perm permission
 +     */
-+    void addPermissions(@NotNull List<Permission> perm);
++    void addPermissions(List<Permission> perm);
 +
 +    /**
 +     * Clears the current registered permissinos.
@@ -211,6 +206,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.plugin.bootstrap;
 +
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents the context provided to a {@link PluginBootstrap} during both the bootstrapping and plugin
@@ -219,6 +215,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * like the plugin's configuration or logger during the plugins bootstrap.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface BootstrapContext extends PluginProviderContext {
 +}
@@ -233,7 +230,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.provider.util.ProviderUtil;
 +import org.bukkit.plugin.java.JavaPlugin;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A plugin bootstrap is meant for loading certain parts of the plugin before the server is loaded.
@@ -245,8 +242,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * <p>
 + * <b>All calls to Bukkit may throw a NullPointerExceptions or return null unexpectedly. You should only call api methods that are explicitly documented to work in the bootstrapper</b>
 + */
-+@ApiStatus.OverrideOnly
 +@ApiStatus.Experimental
++@NullMarked
++@ApiStatus.OverrideOnly
 +public interface PluginBootstrap {
 +
 +    /**
@@ -254,7 +252,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param context the server provided context
 +     */
-+    void bootstrap(@NotNull BootstrapContext context);
++    void bootstrap(BootstrapContext context);
 +
 +    /**
 +     * Called by the server to instantiate your main class.
@@ -264,8 +262,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param context the server created bootstrap object
 +     * @return the server requested instance of the plugins main class.
 +     */
-+    @NotNull
++    default JavaPlugin createPlugin(final PluginProviderContext context) {
-+    default JavaPlugin createPlugin(@NotNull PluginProviderContext context) {
 +        return ProviderUtil.loadClass(context.getConfiguration().getMainClass(), JavaPlugin.class, this.getClass().getClassLoader());
 +    }
 +}
@@ -278,11 +275,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.plugin.bootstrap;
 +
 +import io.papermc.paper.plugin.configuration.PluginMeta;
++import java.nio.file.Path;
 +import net.kyori.adventure.text.logger.slf4j.ComponentLogger;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+
-+import java.nio.file.Path;
 +
 +/**
 + * Represents the context provided to a {@link PluginBootstrap} during both the bootstrapping and plugin
@@ -290,8 +286,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * A bootstrap context may be used to access data or logic usually provided to {@link org.bukkit.plugin.Plugin} instances
 + * like the plugin's configuration or logger during the plugins bootstrap.
 + */
-+@ApiStatus.NonExtendable
 +@ApiStatus.Experimental
++@NullMarked
++@ApiStatus.NonExtendable
 +public interface PluginProviderContext {
 +
 +    /**
@@ -299,7 +296,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the plugin's configuration
 +     */
-+    @NotNull
 +    PluginMeta getConfiguration();
 +
 +    /**
@@ -307,7 +303,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the previously described path
 +     */
-+    @NotNull
 +    Path getDataDirectory();
 +
 +    /**
@@ -315,7 +310,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the logger instance
 +     */
-+    @NotNull
 +    ComponentLogger getLogger();
 +
 +    /**
@@ -323,7 +317,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the previously described path
 +     */
-+    @NotNull
 +    Path getPluginSource();
 +
 +}
@@ -335,21 +328,21 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.plugin.configuration;
 +
++import java.util.List;
 +import org.bukkit.permissions.Permission;
 +import org.bukkit.permissions.PermissionDefault;
 +import org.bukkit.plugin.PluginLoadOrder;
 +import org.bukkit.plugin.java.JavaPlugin;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
-+
-+import java.util.List;
 +
 +/**
 + * This class acts as an abstraction for a plugin configuration.
 + */
-+@ApiStatus.NonExtendable
 +@ApiStatus.Experimental // Subject to change!
++@NullMarked
++@ApiStatus.NonExtendable
 +public interface PluginMeta {
 +
 +    /**
@@ -369,7 +362,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the name of the plugin
 +     */
-+    @NotNull
 +    String getName();
 +
 +    /**
@@ -377,7 +369,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return a descriptive name of the plugin and respective version
 +     */
-+    @NotNull
 +    default String getDisplayName() {
 +        return this.getName() + " v" + this.getVersion();
 +    }
@@ -388,7 +379,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the fully qualified class name of the plugin's main class.
 +     */
-+    @NotNull
 +    String getMainClass();
 +
 +    /**
@@ -397,7 +387,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the plugin load order
 +     * @see PluginLoadOrder for further details regards the available load orders.
 +     */
-+    @NotNull
 +    PluginLoadOrder getLoadOrder();
 +
 +    /**
@@ -407,7 +396,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the string representation of the plugin's version
 +     */
-+    @NotNull
 +    String getVersion();
 +
 +    /**
@@ -418,8 +406,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the specific overwrite of the logger prefix as defined by the plugin. If the plugin did not define a
 +     *     custom logger prefix, this method will return null
 +     */
-+    @Nullable
++    @Nullable String getLoggerPrefix();
-+    String getLoggerPrefix();
 +
 +    /**
 +     * Provides a list of dependencies that are required for this plugin to load.
@@ -430,7 +417,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return an immutable list of required dependency names
 +     */
-+    @NotNull
 +    List<String> getPluginDependencies();
 +
 +    /**
@@ -443,7 +429,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return immutable list of soft dependencies
 +     */
-+    @NotNull
 +    List<String> getPluginSoftDependencies();
 +
 +    /**
@@ -456,7 +441,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return immutable list of plugins to load before this plugin
 +     */
-+    @NotNull
 +    List<String> getLoadBeforePlugins();
 +
 +    /**
@@ -466,7 +450,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return immutable list of provided plugins/dependencies
 +     */
-+    @NotNull
 +    List<String> getProvidedPlugins();
 +
 +    /**
@@ -475,7 +458,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return an immutable list of the plugin's authors
 +     */
-+    @NotNull
 +    List<String> getAuthors();
 +
 +    /**
@@ -484,7 +466,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return an immutable list of the plugin's contributors
 +     */
-+    @NotNull
 +    List<String> getContributors();
 +
 +    /**
@@ -493,8 +474,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return description or null if the plugin did not define a human readable description.
 +     */
-+    @Nullable
++    @Nullable String getDescription();
-+    String getDescription();
 +
 +    /**
 +     * Provides the website for the plugin or the plugin's author.
@@ -502,8 +482,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return a string representation of the website that serves as the main hub for this plugin/its author.
 +     */
-+    @Nullable
++    @Nullable String getWebsite();
-+    String getWebsite();
 +
 +    /**
 +     * Provides the list of permissions that are defined via the plugin meta instance.
@@ -511,7 +490,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return an immutable list of permissions
 +     */
 +    // TODO: Do we even want this? Why not just use the bootstrapper
-+    @NotNull
 +    List<Permission> getPermissions();
 +
 +    /**
@@ -521,7 +499,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see #getPermissions()
 +     */
 +    // TODO: Do we even want this? Why not just use the bootstrapper
-+    @NotNull
 +    PermissionDefault getPermissionDefault();
 +
 +    /**
@@ -532,8 +509,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the version string made up of the major and minor version (e.g. 1.18 or 1.19). Minor versions like 1.18.2
 +     * are unified to their major release version (in this example 1.18)
 +     */
-+    @Nullable
++    @Nullable String getAPIVersion();
-+    String getAPIVersion();
 +
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/configuration/package-info.java b/src/main/java/io/papermc/paper/plugin/configuration/package-info.java
@@ -563,14 +539,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.loader.library.LibraryStore;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A mutable builder that may be used to collect and register all {@link ClassPathLibrary} instances a
 + * {@link PluginLoader} aims to provide to its plugin at runtime.
 + */
-+@ApiStatus.NonExtendable
 +@ApiStatus.Experimental
++@NullMarked
++@ApiStatus.NonExtendable
 +public interface PluginClasspathBuilder {
 +
 +    /**
@@ -587,11 +564,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see io.papermc.paper.plugin.loader.library.impl.JarLibrary
 +     * @see io.papermc.paper.plugin.loader.library.impl.MavenLibraryResolver
 +     */
-+    @NotNull
 +    @Contract("_ -> this")
-+    PluginClasspathBuilder addLibrary(@NotNull ClassPathLibrary classPathLibrary);
++    PluginClasspathBuilder addLibrary(ClassPathLibrary classPathLibrary);
 +
-+    @NotNull
 +    PluginProviderContext getContext();
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/loader/PluginLoader.java b/src/main/java/io/papermc/paper/plugin/loader/PluginLoader.java
@@ -603,7 +578,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.plugin.loader;
 +
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A plugin loader is responsible for creating certain aspects of a plugin before it is created.
@@ -615,8 +590,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * It should be noted that this class will be called from a different classloader, this will cause any static values
 + * set in this class/any other classes loaded not to persist when the plugin loads.
 + */
-+@ApiStatus.OverrideOnly
 +@ApiStatus.Experimental
++@NullMarked
++@ApiStatus.OverrideOnly
 +public interface PluginLoader {
 +
 +    /**
@@ -627,7 +603,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param classpathBuilder a mutable classpath builder that may be used to register custom runtime dependencies
 +     *                         for the plugin the loader was registered for.
 +     */
-+    void classloader(@NotNull PluginClasspathBuilder classpathBuilder);
++    void classloader(PluginClasspathBuilder classpathBuilder);
 +
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/loader/library/ClassPathLibrary.java b/src/main/java/io/papermc/paper/plugin/loader/library/ClassPathLibrary.java
@@ -638,12 +614,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.plugin.loader.library;
 +
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * The classpath library interface represents libraries that are capable of registering themselves via
 + * {@link #register(LibraryStore)} on any given {@link LibraryStore}.
 + */
++@NullMarked
 +public interface ClassPathLibrary {
 +
 +    /**
@@ -654,7 +631,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param store the library store instance to register this library into
 +     * @throws LibraryLoadingException if library loading failed for this classpath library
 +     */
-+    void register(@NotNull LibraryStore store) throws LibraryLoadingException;
++    void register(LibraryStore store) throws LibraryLoadingException;
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/loader/library/LibraryLoadingException.java b/src/main/java/io/papermc/paper/plugin/loader/library/LibraryLoadingException.java
 new file mode 100644
@@ -685,10 +662,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 @@ -0,0 +0,0 @@
 +package io.papermc.paper.plugin.loader.library;
 +
-+import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
-+
 +import java.nio.file.Path;
++import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents a storage that stores library jars.
@@ -699,6 +675,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see io.papermc.paper.plugin.loader.PluginLoader
 + */
 +@ApiStatus.Internal
++@NullMarked
 +public interface LibraryStore {
 +
 +    /**
@@ -706,7 +683,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param library path to the libraries jar file on the disk
 +     */
-+    void addLibrary(@NotNull Path library);
++    void addLibrary(Path library);
 +
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/loader/library/impl/JarLibrary.java b/src/main/java/io/papermc/paper/plugin/loader/library/impl/JarLibrary.java
@@ -720,10 +697,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.loader.library.ClassPathLibrary;
 +import io.papermc.paper.plugin.loader.library.LibraryLoadingException;
 +import io.papermc.paper.plugin.loader.library.LibraryStore;
-+import org.jetbrains.annotations.NotNull;
-+
 +import java.nio.file.Files;
 +import java.nio.file.Path;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A simple jar library implementation of the {@link ClassPathLibrary} that allows {@link io.papermc.paper.plugin.loader.PluginLoader}s to
@@ -738,6 +714,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * <p>
 + * The jar library implementation will error if the file does not exist at the specified path.
 + */
++@NullMarked
 +public class JarLibrary implements ClassPathLibrary {
 +
 +    private final Path path;
@@ -747,12 +724,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @param path the path, relative to the JVMs start directory.
 +     */
-+    public JarLibrary(@NotNull Path path) {
++    public JarLibrary(final Path path) {
 +        this.path = path;
 +    }
 +
 +    @Override
-+    public void register(@NotNull LibraryStore store) throws LibraryLoadingException {
++    public void register(final LibraryStore store) throws LibraryLoadingException {
 +        if (Files.notExists(this.path)) {
 +            throw new LibraryLoadingException("Could not find library at " + this.path);
 +        }
@@ -771,6 +748,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.loader.library.ClassPathLibrary;
 +import io.papermc.paper.plugin.loader.library.LibraryLoadingException;
 +import io.papermc.paper.plugin.loader.library.LibraryStore;
++import java.io.File;
++import java.util.ArrayList;
++import java.util.List;
 +import org.apache.maven.repository.internal.MavenRepositorySystemUtils;
 +import org.eclipse.aether.DefaultRepositorySystemSession;
 +import org.eclipse.aether.RepositorySystem;
@@ -791,14 +771,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.eclipse.aether.transfer.TransferCancelledException;
 +import org.eclipse.aether.transfer.TransferEvent;
 +import org.eclipse.aether.transport.http.HttpTransporterFactory;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +import org.slf4j.Logger;
 +import org.slf4j.LoggerFactory;
 +
-+import java.io.File;
-+import java.util.ArrayList;
-+import java.util.List;
-+
 +/**
 + * The maven library resolver acts as a resolver for yet to be resolved jar libraries that may be pulled from a
 + * remote maven repository.
@@ -813,12 +789,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + *     "central", "default", "https://repo1.maven.org/maven2/"
 + * ).build());
 + * }</pre>
-+ *
++ * <p>
 + * Plugins may create and register a {@link MavenLibraryResolver} after configuring it.
 + */
++@NullMarked
 +public class MavenLibraryResolver implements ClassPathLibrary {
 +
-+    private static final Logger logger = LoggerFactory.getLogger("MavenLibraryResolver");
++    private static final Logger LOGGER = LoggerFactory.getLogger("MavenLibraryResolver");
 +
 +    private final RepositorySystem repository;
 +    private final DefaultRepositorySystemSession session;
@@ -834,7 +811,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * submitting the {@link MavenLibraryResolver} to the {@link io.papermc.paper.plugin.loader.PluginClasspathBuilder}.
 +     */
 +    public MavenLibraryResolver() {
-+        DefaultServiceLocator locator = MavenRepositorySystemUtils.newServiceLocator();
++        final DefaultServiceLocator locator = MavenRepositorySystemUtils.newServiceLocator();
 +        locator.addService(RepositoryConnectorFactory.class, BasicRepositoryConnectorFactory.class);
 +        locator.addService(TransporterFactory.class, HttpTransporterFactory.class);
 +
@@ -846,8 +823,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        this.session.setLocalRepositoryManager(this.repository.newLocalRepositoryManager(this.session, new LocalRepository("libraries")));
 +        this.session.setTransferListener(new AbstractTransferListener() {
 +            @Override
-+            public void transferInitiated(@NotNull TransferEvent event) throws TransferCancelledException {
++            public void transferInitiated(final TransferEvent event) throws TransferCancelledException {
-+                logger.info("Downloading {}", event.getResource().getRepositoryUrl() + event.getResource().getResourceName());
++                LOGGER.info("Downloading {}", event.getResource().getRepositoryUrl() + event.getResource().getResourceName());
 +            }
 +        });
 +        this.session.setReadOnly();
@@ -860,7 +837,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param dependency the definition of the dependency the maven library resolver should resolve when running
 +     * @see MavenLibraryResolver#addRepository(RemoteRepository)
 +     */
-+    public void addDependency(@NotNull Dependency dependency) {
++    public void addDependency(final Dependency dependency) {
 +        this.dependencies.add(dependency);
 +    }
 +
@@ -872,7 +849,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param remoteRepository the configuration that defines the maven repository this library resolver should fetch
 +     * dependencies from
 +     */
-+    public void addRepository(@NotNull RemoteRepository remoteRepository) {
++    public void addRepository(final RemoteRepository remoteRepository) {
 +        this.repositories.add(remoteRepository);
 +    }
 +
@@ -883,18 +860,18 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @throws LibraryLoadingException if resolving a dependency failed
 +     */
 +    @Override
-+    public void register(@NotNull LibraryStore store) throws LibraryLoadingException {
++    public void register(final LibraryStore store) throws LibraryLoadingException {
-+        List<RemoteRepository> repos = this.repository.newResolutionRepositories(this.session, this.repositories);
++        final List<RemoteRepository> repos = this.repository.newResolutionRepositories(this.session, this.repositories);
 +
-+        DependencyResult result;
++        final DependencyResult result;
 +        try {
 +            result = this.repository.resolveDependencies(this.session, new DependencyRequest(new CollectRequest((Dependency) null, this.dependencies, repos), null));
-+        } catch (DependencyResolutionException ex) {
++        } catch (final DependencyResolutionException ex) {
 +            throw new LibraryLoadingException("Error resolving libraries", ex);
 +        }
 +
-+        for (ArtifactResult artifact : result.getArtifactResults()) {
++        for (final ArtifactResult artifact : result.getArtifactResults()) {
-+            File file = artifact.getArtifact().getFile();
++            final File file = artifact.getArtifact().getFile();
 +            store.addLibrary(file.toPath());
 +        }
 +    }
@@ -908,7 +885,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.plugin.provider.classloader;
 +
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * The class loader access interface is an <b>internal</b> representation of a class accesses' ability to see types
@@ -919,6 +896,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * is owned by a direct or transitive dependency of the plugin, preventing the plugin for accidentally discovering and
 + * using class types that are supplied by plugins/libraries the plugin did not actively define as a dependency.
 + */
++@NullMarked
 +@ApiStatus.Internal
 +public interface ClassLoaderAccess {
 +
@@ -948,12 +926,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.plugin.provider.classloader;
 +
 +import io.papermc.paper.plugin.configuration.PluginMeta;
++import java.io.Closeable;
 +import org.bukkit.plugin.java.JavaPlugin;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+
++import org.jspecify.annotations.Nullable;
-+import java.io.Closeable;
-+import org.jetbrains.annotations.Nullable;
 +
 +/**
 + * The configured plugin class loader represents an <b>internal</b> abstraction over the classloaders used by the server
@@ -962,6 +939,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * It implements {@link Closeable} to define the ability to shutdown and close the classloader that implements this
 + * interface.
 + */
++@NullMarked
 +@ApiStatus.Internal
 +public interface ConfiguredPluginClassLoader extends Closeable {
 +
@@ -987,7 +965,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see ClassLoader#loadClass(String)
 +     * @see Class#forName(String, boolean, ClassLoader)
 +     */
-+    Class<?> loadClass(@NotNull String name,
++    Class<?> loadClass(String name,
 +                       boolean resolve,
 +                       boolean checkGlobal,
 +                       boolean checkLibraries) throws ClassNotFoundException;
@@ -1013,8 +991,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * that is used by the underlying classloader
 +     * @return classloader
 +     */
-+    @Nullable
++    @Nullable PluginClassLoaderGroup getGroup();
-+    PluginClassLoaderGroup getGroup();
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/provider/classloader/PaperClassLoaderStorage.java b/src/main/java/io/papermc/paper/plugin/provider/classloader/PaperClassLoaderStorage.java
 new file mode 100644
@@ -1147,7 +1124,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * A plugin classloader group represents a group of classloaders that a plugins classloader may access.
@@ -1155,6 +1133,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * An example of this would be a classloader group that holds all direct and transitive dependencies a plugin declared,
 + * allowing a plugins classloader to access classes included in these dependencies via this group.
 + */
++@NullMarked
 +@ApiStatus.Internal
 +public interface PluginClassLoaderGroup {
 +
@@ -1172,8 +1151,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * will be returned.
 +     * @see ConfiguredPluginClassLoader#loadClass(String, boolean, boolean, boolean)
 +     */
-+    @Nullable
++    @Nullable Class<?> getClassByName(String name, boolean resolve, ConfiguredPluginClassLoader requester);
-+    Class<?> getClassByName(String name, boolean resolve, ConfiguredPluginClassLoader requester);
 +
 +    /**
 +     * Removes a configured plugin classloader from this class loader group.
@@ -1218,7 +1196,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import io.papermc.paper.plugin.configuration.PluginMeta;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A dependency context is a read-only abstraction of a type/concept that can resolve dependencies between plugins.
@@ -1226,6 +1204,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * This may for example be the server wide plugin manager itself, capable of validating if a dependency exists between
 + * two {@link PluginMeta} instances, however the implementation is not limited to such a concrete use-case.
 + */
++@NullMarked
 +@ApiStatus.Internal
 +public interface DependencyContext {
 +
@@ -1245,7 +1224,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param depend the potential transitive dependency of the {@code plugin} parameter.
 +     * @return a simple boolean flag indicating if {@code plugin} considers {@code depend} as a transitive dependency.
 +     */
-+    boolean isTransitiveDependency(@NotNull PluginMeta plugin, @NotNull PluginMeta depend);
++    boolean isTransitiveDependency(PluginMeta plugin, PluginMeta depend);
 +
 +    /**
 +     * Computes if this dependency context is aware of a dependency that provides/matches the passed identifier.
@@ -1259,7 +1238,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return a plain boolean flag indicating if this dependency context is aware of a potential dependency with the
 +     * passed identifier.
 +     */
-+    boolean hasDependency(@NotNull String pluginIdentifier);
++    boolean hasDependency(String pluginIdentifier);
 +
 +}
 diff --git a/src/main/java/io/papermc/paper/plugin/provider/util/ProviderUtil.java b/src/main/java/io/papermc/paper/plugin/provider/util/ProviderUtil.java
@@ -1272,16 +1251,17 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import com.destroystokyo.paper.util.SneakyThrow;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
 +/**
 + * An <b>internal</b> utility type that holds logic for loading a provider-like type from a classloaders.
 + * Provides, at least in the context of this utility, define themselves as implementations of a specific parent
 + * interface/type, e.g. {@link org.bukkit.plugin.java.JavaPlugin} and implement a no-args constructor.
 + */
++@NullMarked
 +@ApiStatus.Internal
-+public class ProviderUtil {
++public final class ProviderUtil {
 +
 +    /**
 +     * Loads the class found at the provided fully qualified class name from the passed classloader, creates a new
@@ -1294,8 +1274,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T>       the generic type of the parent class the created object will be cast to
 +     * @return the object instantiated from the class found at the provided FQN, cast to the parent type
 +     */
-+    @NotNull
++    public static <T> T loadClass(final String clazz, final Class<T> classType, final ClassLoader loader) {
-+    public static <T> T loadClass(@NotNull String clazz, @NotNull Class<T> classType, @NotNull ClassLoader loader) {
 +        return loadClass(clazz, classType, loader, null);
 +    }
 +
@@ -1312,30 +1291,29 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the object instantiated from the class found at the provided fully qualified class name, cast to the
 +     * parent type
 +     */
-+    @NotNull
++    public static <T> T loadClass(final String clazz, final Class<T> classType, final ClassLoader loader, final @Nullable Runnable onError) {
-+    public static <T> T loadClass(@NotNull String clazz, @NotNull Class<T> classType, @NotNull ClassLoader loader, @Nullable Runnable onError) {
 +        try {
-+            T clazzInstance;
++            final T clazzInstance;
 +
 +            try {
-+                Class<?> jarClass = Class.forName(clazz, true, loader);
++                final Class<?> jarClass = Class.forName(clazz, true, loader);
 +
-+                Class<? extends T> pluginClass;
++                final Class<? extends T> pluginClass;
 +                try {
 +                    pluginClass = jarClass.asSubclass(classType);
-+                } catch (ClassCastException ex) {
++                } catch (final ClassCastException ex) {
 +                    throw new ClassCastException("class '%s' does not extend '%s'".formatted(clazz, classType));
 +                }
 +
 +                clazzInstance = pluginClass.getDeclaredConstructor().newInstance();
-+            } catch (IllegalAccessException exception) {
++            } catch (final IllegalAccessException exception) {
 +                throw new RuntimeException("No public constructor");
-+            } catch (InstantiationException exception) {
++            } catch (final InstantiationException exception) {
 +                throw new RuntimeException("Abnormal class instantiation", exception);
 +            }
 +
 +            return clazzInstance;
-+        } catch (Throwable e) {
++        } catch (final Throwable e) {
 +            if (onError != null) {
 +                onError.run();
 +            }

patches/api/PlayerAttemptPickupItemEvent.patch

@@ -17,16 +17,17 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.event.Cancellable;
 +import org.bukkit.event.HandlerList;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Thrown when a player attempts to pick an item up from the ground
 + */
++@NullMarked
 +public class PlayerAttemptPickupItemEvent extends PlayerEvent implements Cancellable {
 +
 +    private static final HandlerList HANDLER_LIST = new HandlerList();
 +
-+    @NotNull private final Item item;
++    private final Item item;
 +    private final int remaining;
 +    private boolean flyAtPlayer = true;
 +
@@ -34,12 +35,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +    @Deprecated // Remove in 1.13 // Remove in 1.14?
 +    @ApiStatus.Internal
-+    public PlayerAttemptPickupItemEvent(@NotNull final Player player, @NotNull final Item item) {
++    public PlayerAttemptPickupItemEvent(final Player player, final Item item) {
 +        this(player, item, 0);
 +    }
 +
 +    @ApiStatus.Internal
-+    public PlayerAttemptPickupItemEvent(@NotNull final Player player, @NotNull final Item item, final int remaining) {
++    public PlayerAttemptPickupItemEvent(final Player player, final Item item, final int remaining) {
 +        super(player);
 +        this.item = item;
 +        this.remaining = remaining;
@@ -50,7 +51,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return Item
 +     */
-+    @NotNull
 +    public Item getItem() {
 +        return this.item;
 +    }
@@ -95,13 +95,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        this.flyAtPlayer = !cancel;
 +    }
 +
-+    @NotNull
 +    @Override
 +    public HandlerList getHandlers() {
 +        return HANDLER_LIST;
 +    }
 +
-+    @NotNull
 +    public static HandlerList getHandlerList() {
 +        return HANDLER_LIST;
 +    }

patches/api/Registry-Modification-API.patch

@@ -13,14 +13,16 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.registry;
 +
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * To be implemented by any type used for modifying registries.
 + *
 + * @param <T> registry value type
 + */
-+@ApiStatus.NonExtendable
 +@ApiStatus.Experimental
++@NullMarked
++@ApiStatus.NonExtendable
 +public interface RegistryBuilder<T> {
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/event/RegistryEntryAddEvent.java b/src/main/java/io/papermc/paper/registry/event/RegistryEntryAddEvent.java
@@ -36,8 +38,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.tag.Tag;
 +import io.papermc.paper.registry.tag.TagKey;
 +import org.bukkit.Keyed;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Event object for {@link RegistryEventProvider#entryAdd()}. This
@@ -48,6 +50,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <B> registry entry builder type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface RegistryEntryAddEvent<T, B extends RegistryBuilder<T>> extends RegistryEvent<T> {
 +
@@ -56,14 +59,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the object builder
 +     */
-+    @NonNull B builder();
++    B builder();
 +
 +    /**
 +     * Gets the key for this entry in the registry.
 +     *
 +     * @return the key
 +     */
-+    @NonNull TypedKey<T> key();
++    TypedKey<T> key();
 +
 +    /**
 +     * Gets or creates a tag for the given tag key. This tag
@@ -74,7 +77,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the tag
 +     * @param <V> the tag value type
 +     */
-+    @NonNull <V extends Keyed> Tag<V> getOrCreateTag(@NonNull TagKey<V> tagKey);
++    <V extends Keyed> Tag<V> getOrCreateTag(TagKey<V> tagKey);
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/event/RegistryEvent.java b/src/main/java/io/papermc/paper/registry/event/RegistryEvent.java
 new file mode 100644
@@ -86,8 +89,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import io.papermc.paper.plugin.lifecycle.event.LifecycleEvent;
 +import io.papermc.paper.registry.RegistryKey;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Base type for all registry events.
@@ -95,6 +98,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <T> registry entry type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface RegistryEvent<T> extends LifecycleEvent {
 +
@@ -103,7 +107,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the registry key
 +     */
-+    @NonNull RegistryKey<T> registryKey();
++    RegistryKey<T> registryKey();
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/event/RegistryEventProvider.java b/src/main/java/io/papermc/paper/registry/event/RegistryEventProvider.java
 new file mode 100644
@@ -115,14 +119,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import io.papermc.paper.plugin.bootstrap.BootstrapContext;
 +import io.papermc.paper.plugin.lifecycle.event.handler.LifecycleEventHandler;
-+import io.papermc.paper.plugin.lifecycle.event.handler.configuration.LifecycleEventHandlerConfiguration;
-+import io.papermc.paper.plugin.lifecycle.event.handler.configuration.PrioritizedLifecycleEventHandlerConfiguration;
 +import io.papermc.paper.plugin.lifecycle.event.types.LifecycleEventType;
 +import io.papermc.paper.registry.RegistryBuilder;
 +import io.papermc.paper.registry.RegistryKey;
 +import io.papermc.paper.registry.event.type.RegistryEntryAddEventType;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Provider for registry events for a specific registry.
@@ -137,6 +139,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <B> registry entry builder type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface RegistryEventProvider<T, B extends RegistryBuilder<T>> {
 +
@@ -149,7 +152,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the registry entry add event type
 +     */
-+    @NonNull RegistryEntryAddEventType<T, B> entryAdd();
++    RegistryEntryAddEventType<T, B> entryAdd();
 +
 +    /**
 +     * Gets the event type for {@link RegistryFreezeEvent} which is fired just before
@@ -160,14 +163,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the registry freeze event type
 +     */
-+    LifecycleEventType.@NonNull Prioritizable<BootstrapContext, RegistryFreezeEvent<T, B>> freeze();
++    LifecycleEventType.Prioritizable<BootstrapContext, RegistryFreezeEvent<T, B>> freeze();
 +
 +    /**
 +     * Gets the registry key associated with this event type provider.
 +     *
 +     * @return the registry key
 +     */
-+    @NonNull RegistryKey<T> registryKey();
++    RegistryKey<T> registryKey();
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/event/RegistryEventProviderImpl.java b/src/main/java/io/papermc/paper/registry/event/RegistryEventProviderImpl.java
 new file mode 100644
@@ -182,12 +185,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.RegistryBuilder;
 +import io.papermc.paper.registry.RegistryKey;
 +import io.papermc.paper.registry.event.type.RegistryEntryAddEventType;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.framework.qual.DefaultQualifier;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
-+@DefaultQualifier(NonNull.class)
++@NullMarked
 +record RegistryEventProviderImpl<T, B extends RegistryBuilder<T>>(RegistryKey<T> registryKey) implements RegistryEventProvider<T, B> {
 +
 +    static <T, B extends RegistryBuilder<T>> RegistryEventProvider<T, B> create(final RegistryKey<T> registryKey) {
@@ -244,12 +246,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.registry.event;
 +
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Holds providers for {@link RegistryEntryAddEvent} and {@link RegistryFreezeEvent}
 + * handlers for each applicable registry.
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public final class RegistryEvents {
 +
 +    private RegistryEvents() {
@@ -267,8 +271,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.tag.Tag;
 +import io.papermc.paper.registry.tag.TagKey;
 +import org.bukkit.Keyed;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Event object for {@link RegistryEventProvider#freeze()}. This
@@ -279,6 +283,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <B> registry entry builder type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface RegistryFreezeEvent<T, B extends RegistryBuilder<T>> extends RegistryEvent<T> {
 +
@@ -287,7 +292,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return a writable registry
 +     */
-+    @NonNull WritableRegistry<T, B> registry();
++    WritableRegistry<T, B> registry();
 +
 +    /**
 +     * Gets or creates a tag for the given tag key. This tag
@@ -298,7 +303,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the tag
 +     * @param <V> the tag value type
 +     */
-+    @NonNull <V extends Keyed> Tag<V> getOrCreateTag(@NonNull TagKey<V> tagKey);
++    <V extends Keyed> Tag<V> getOrCreateTag(TagKey<V> tagKey);
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/event/WritableRegistry.java b/src/main/java/io/papermc/paper/registry/event/WritableRegistry.java
 new file mode 100644
@@ -311,8 +316,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.RegistryBuilder;
 +import io.papermc.paper.registry.TypedKey;
 +import java.util.function.Consumer;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A registry which supports registering new objects.
@@ -320,8 +325,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <T> registry entry type
 + * @param <B> registry entry builder type
 + */
-+@ApiStatus.NonExtendable
 +@ApiStatus.Experimental
++@NullMarked
++@ApiStatus.NonExtendable
 +public interface WritableRegistry<T, B extends RegistryBuilder<T>> {
 +
 +    /**
@@ -331,7 +337,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param key the entry's key (must be unique from others)
 +     * @param value a consumer for the entry's builder
 +     */
-+    void register(@NonNull TypedKey<T> key, @NonNull Consumer<? super B> value);
++    void register(TypedKey<T> key, Consumer<? super B> value);
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/event/type/RegistryEntryAddConfiguration.java b/src/main/java/io/papermc/paper/registry/event/type/RegistryEntryAddConfiguration.java
 new file mode 100644
@@ -345,14 +351,15 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.plugin.lifecycle.event.handler.configuration.PrioritizedLifecycleEventHandlerConfiguration;
 +import io.papermc.paper.registry.TypedKey;
 +import java.util.function.Predicate;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.Contract;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Specific configuration for {@link io.papermc.paper.registry.event.RegistryEntryAddEvent}s.
 + *
 + * @param <T> registry entry type
 + */
++@NullMarked
 +public interface RegistryEntryAddConfiguration<T> extends PrioritizedLifecycleEventHandlerConfiguration<BootstrapContext> {
 +
 +    /**
@@ -362,7 +369,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return this configuration
 +     */
 +    @Contract(value = "_ -> this", mutates = "this")
-+    default @NonNull RegistryEntryAddConfiguration<T> filter(final @NonNull TypedKey<T> key) {
++    default RegistryEntryAddConfiguration<T> filter(final TypedKey<T> key) {
 +        return this.filter(key::equals);
 +    }
 +
@@ -373,13 +380,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return this configuration
 +     */
 +    @Contract(value = "_ -> this", mutates = "this")
-+    @NonNull RegistryEntryAddConfiguration<T> filter(@NonNull Predicate<TypedKey<T>> filter);
++    RegistryEntryAddConfiguration<T> filter(Predicate<TypedKey<T>> filter);
 +
 +    @Override
-+    @NonNull RegistryEntryAddConfiguration<T> priority(int priority);
++    RegistryEntryAddConfiguration<T> priority(int priority);
 +
 +    @Override
-+    @NonNull RegistryEntryAddConfiguration<T> monitor();
++    RegistryEntryAddConfiguration<T> monitor();
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/event/type/RegistryEntryAddEventType.java b/src/main/java/io/papermc/paper/registry/event/type/RegistryEntryAddEventType.java
 new file mode 100644
@@ -394,6 +401,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.RegistryBuilder;
 +import io.papermc.paper.registry.event.RegistryEntryAddEvent;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Lifecycle event type for {@link RegistryEntryAddEvent}s.
@@ -402,6 +410,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <B> registry entry builder type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface RegistryEntryAddEventType<T, B extends RegistryBuilder<T>> extends LifecycleEventType<BootstrapContext, RegistryEntryAddEvent<T, B>, RegistryEntryAddConfiguration<T>> {
 +}
@@ -418,11 +427,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Iterator;
 +import org.bukkit.Keyed;
 +import org.bukkit.Registry;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public non-sealed interface RegistryKeySet<T extends Keyed> extends Iterable<TypedKey<T>>, RegistrySet<T> { // TODO remove Keyed
 +
@@ -436,7 +446,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the keys
 +     */
-+    @NonNull @Unmodifiable Collection<TypedKey<T>> values();
++    @Unmodifiable Collection<TypedKey<T>> values();
 +
 +    /**
 +     * Resolve this set into a collection of values. Prefer using
@@ -446,7 +456,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the resolved values
 +     * @see RegistryKeySet#values()
 +     */
-+    @NonNull @Unmodifiable Collection<T> resolve(final @NonNull Registry<T> registry);
++    @Unmodifiable Collection<T> resolve(final Registry<T> registry);
 +
 +    /**
 +     * Checks if this set contains the value with the given key.
@@ -454,10 +464,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param valueKey the key to check
 +     * @return true if the value is in this set
 +     */
-+    boolean contains(@NonNull TypedKey<T> valueKey);
++    boolean contains(TypedKey<T> valueKey);
 +
 +    @Override
-+    default @NonNull Iterator<TypedKey<T>> iterator() {
++    default Iterator<TypedKey<T>> iterator() {
 +        return this.values().iterator();
 +    }
 +}
@@ -480,20 +490,19 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.Keyed;
 +import org.bukkit.NamespacedKey;
 +import org.bukkit.Registry;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.framework.qual.DefaultQualifier;
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.NullMarked;
++import org.jspecify.annotations.Nullable;
 +
 +@ApiStatus.Internal
-+@DefaultQualifier(NonNull.class)
++@NullMarked
-+record RegistryKeySetImpl<T extends Keyed>(RegistryKey<T> registryKey, List<TypedKey<T>> values) implements RegistryKeySet<T> { // TODO remove Keyed
++record RegistryKeySetImpl<T extends @Nullable Keyed>(RegistryKey<T> registryKey, List<TypedKey<T>> values) implements RegistryKeySet<T> { // TODO remove Keyed
 +
 +    static <T extends Keyed> RegistryKeySet<T> create(final RegistryKey<T> registryKey, final Iterable<? extends T> values) { // TODO remove Keyed
 +        final Registry<T> registry = RegistryAccess.registryAccess().getRegistry(registryKey);
 +        final ArrayList<TypedKey<T>> keys = new ArrayList<>();
 +        for (final T value : values) {
-+            final @Nullable NamespacedKey key = registry.getKey(value);
++            final NamespacedKey key = registry.getKey(value);
 +            Preconditions.checkArgument(key != null, value + " does not have a key in " + registryKey);
 +            keys.add(TypedKey.create(registryKey, key));
 +        }
@@ -513,7 +522,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    public Collection<T> resolve(final Registry<T> registry) {
 +        final List<T> values = new ArrayList<>(this.values.size());
 +        for (final TypedKey<T> key : this.values) {
-+            final @Nullable T value = registry.get(key.key());
++            final T value = registry.get(key.key());
 +            Preconditions.checkState(value != null, "Trying to access unbound TypedKey: " + key);
 +            values.add(value);
 +        }
@@ -533,9 +542,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.TypedKey;
 +import io.papermc.paper.registry.tag.Tag;
 +import org.bukkit.Keyed;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents a collection tied to a registry.
@@ -553,6 +562,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <T> registry value type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public sealed interface RegistrySet<T> permits RegistryKeySet, RegistryValueSet {
 +
 +    // TODO uncomment when direct holder sets need to be exposed to the API
@@ -566,7 +576,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    //  * @param <T> the type of the values
 +    //  */
 +    // @Contract(value = "_, _ -> new", pure = true)
-+    // static <T> @NonNull RegistryValueSet<T> valueSet(final @NonNull RegistryKey<T> registryKey, final @NonNull Iterable<? extends T> values) {
++    // static <T> RegistryValueSet<T> valueSet(final RegistryKey<T> registryKey, final Iterable<? extends T> values) {
 +    //     return RegistryValueSetImpl.create(registryKey, values);
 +    // }
 +
@@ -584,7 +594,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @throws IllegalArgumentException if the registry isn't available yet or if any value doesn't have a key in that registry
 +     */
 +    @Contract(value = "_, _ -> new", pure = true)
-+    static <T extends Keyed> @NonNull RegistryKeySet<T> keySetFromValues(final @NonNull RegistryKey<T> registryKey, final @NonNull Iterable<? extends T> values) { // TODO remove Keyed
++    static <T extends Keyed> RegistryKeySet<T> keySetFromValues(final RegistryKey<T> registryKey, final Iterable<? extends T> values) { // TODO remove Keyed
 +        return RegistryKeySetImpl.create(registryKey, values);
 +    }
 +
@@ -597,7 +607,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the type of the values
 +     */
 +    @SafeVarargs
-+    static <T extends Keyed> RegistryKeySet<T> keySet(final @NonNull RegistryKey<T> registryKey, final @NonNull TypedKey<T> @NonNull... keys) { // TODO remove Keyed
++    static <T extends Keyed> RegistryKeySet<T> keySet(final RegistryKey<T> registryKey, final TypedKey<T>... keys) { // TODO remove Keyed
 +        return keySet(registryKey, Lists.newArrayList(keys));
 +    }
 +
@@ -611,7 +621,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @SuppressWarnings("BoundedWildcard")
 +    @Contract(value = "_, _ -> new", pure = true)
-+    static <T extends Keyed> @NonNull RegistryKeySet<T> keySet(final @NonNull RegistryKey<T> registryKey, final @NonNull Iterable<TypedKey<T>> keys) { // TODO remove Keyed
++    static <T extends Keyed> RegistryKeySet<T> keySet(final RegistryKey<T> registryKey, final Iterable<TypedKey<T>> keys) { // TODO remove Keyed
 +        return new RegistryKeySetImpl<>(registryKey, Lists.newArrayList(keys));
 +    }
 +
@@ -620,7 +630,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the registry key
 +     */
-+    @NonNull RegistryKey<T> registryKey();
++    RegistryKey<T> registryKey();
 +
 +    /**
 +     * Get the size of this set.
@@ -648,9 +658,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import java.util.Collection;
 +import java.util.Iterator;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A collection of anonymous values relating to a registry. These
@@ -659,6 +669,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @param <T> registry value type
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public sealed interface RegistryValueSet<T> extends Iterable<T>, RegistrySet<T> permits RegistryValueSetImpl {
 +
 +    @Override
@@ -671,10 +682,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the values
 +     */
-+    @NonNull @Unmodifiable Collection<T> values();
++    @Unmodifiable Collection<T> values();
 +
 +    @Override
-+    default @NonNull Iterator<T> iterator() {
++    default Iterator<T> iterator() {
 +        return this.values().iterator();
 +    }
 +}
@@ -690,8 +701,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.RegistryKey;
 +import java.util.List;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
++@NullMarked
 +record RegistryValueSetImpl<T>(RegistryKey<T> registryKey, List<T> values) implements RegistryValueSet<T> {
 +
 +    RegistryValueSetImpl {
@@ -712,8 +725,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import io.papermc.paper.registry.set.RegistryKeySet;
 +import org.bukkit.Keyed;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A named {@link RegistryKeySet} which are created
@@ -724,6 +737,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see org.bukkit.Registry#getTag(TagKey)
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +public interface Tag<T extends Keyed> extends RegistryKeySet<T> { // TODO remove Keyed
 +
 +    /**
@@ -731,7 +745,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the tag key identifier
 +     */
-+    @NonNull TagKey<T> tagKey();
++    TagKey<T> tagKey();
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/tag/TagKey.java b/src/main/java/io/papermc/paper/registry/tag/TagKey.java
 new file mode 100644
@@ -744,11 +758,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.RegistryKey;
 +import net.kyori.adventure.key.Key;
 +import net.kyori.adventure.key.Keyed;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Experimental
++@NullMarked
 +public sealed interface TagKey<T> extends Keyed permits TagKeyImpl {
 +
 +    /**
@@ -760,7 +775,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the registry value type
 +     */
 +    @Contract(value = "_, _ -> new", pure = true)
-+    static <T> @NonNull TagKey<T> create(final @NonNull RegistryKey<T> registryKey, final @NonNull Key key) {
++    static <T> TagKey<T> create(final RegistryKey<T> registryKey, final Key key) {
 +        return new TagKeyImpl<>(registryKey, key);
 +    }
 +
@@ -769,7 +784,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the registry key
 +     */
-+    @NonNull RegistryKey<T> registryKey();
++    RegistryKey<T> registryKey();
 +}
 diff --git a/src/main/java/io/papermc/paper/registry/tag/TagKeyImpl.java b/src/main/java/io/papermc/paper/registry/tag/TagKeyImpl.java
 new file mode 100644
@@ -781,12 +796,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import io.papermc.paper.registry.RegistryKey;
 +import net.kyori.adventure.key.Key;
-+import org.checkerframework.checker.nullness.qual.NonNull;
-+import org.checkerframework.framework.qual.DefaultQualifier;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
-+@DefaultQualifier(NonNull.class)
++@NullMarked
 +record TagKeyImpl<T>(RegistryKey<T> registryKey, Key key) implements TagKey<T> {
 +
 +    @Override

patches/api/Suspicious-Effect-Entry-API.patch

@@ -24,11 +24,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.potion.PotionEffect;
 +import org.bukkit.potion.PotionEffectType;
 +import org.jetbrains.annotations.Contract;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents a {@link PotionEffectType} paired with a duration.
 + */
++@NullMarked
 +public sealed interface SuspiciousEffectEntry permits SuspiciousEffectEntryImpl {
 +
 +    /**
@@ -36,7 +37,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return effect type
 +     */
-+    @NotNull PotionEffectType effect();
++    PotionEffectType effect();
 +
 +    /**
 +     * Gets the duration for this effect instance.
@@ -53,7 +54,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return new instance of an entry
 +     */
 +    @Contract(value = "_, _ -> new", pure = true)
-+    static @NotNull SuspiciousEffectEntry create(final @NotNull PotionEffectType effectType, final int duration) {
++    static SuspiciousEffectEntry create(final PotionEffectType effectType, final int duration) {
 +        return new SuspiciousEffectEntryImpl(effectType, duration);
 +    }
 +}
@@ -66,9 +67,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.potion;
 +
 +import org.bukkit.potion.PotionEffectType;
-+import org.jetbrains.annotations.NotNull;
++import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
-+record SuspiciousEffectEntryImpl(@NotNull PotionEffectType effect, int duration) implements SuspiciousEffectEntry {
++@ApiStatus.Internal
++@NullMarked
++record SuspiciousEffectEntryImpl(PotionEffectType effect, int duration) implements SuspiciousEffectEntry {
 +}
 diff --git a/src/main/java/org/bukkit/entity/MushroomCow.java b/src/main/java/org/bukkit/entity/MushroomCow.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644

patches/api/Tag-Lifecycle-Events.patch

@@ -45,8 +45,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.RegistryKey;
 +import io.papermc.paper.tag.PostFlattenTagRegistrar;
 +import io.papermc.paper.tag.PreFlattenTagRegistrar;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Provides event types for tag registration.
@@ -55,6 +55,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see PostFlattenTagRegistrar
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface TagEventTypeProvider {
 +
@@ -66,7 +67,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the type of value in the tag
 +     * @see PreFlattenTagRegistrar
 +     */
-+    <T> LifecycleEventType.@NonNull Prioritizable<BootstrapContext, ReloadableRegistrarEvent<PreFlattenTagRegistrar<T>>> preFlatten(@NonNull RegistryKey<T> registryKey);
++    <T> LifecycleEventType.Prioritizable<BootstrapContext, ReloadableRegistrarEvent<PreFlattenTagRegistrar<T>>> preFlatten(RegistryKey<T> registryKey);
 +
 +    /**
 +     * Get a prioritizable, reloadable registrar event for tags after they are flattened.
@@ -76,7 +77,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the type of value in the tag
 +     * @see PostFlattenTagRegistrar
 +     */
-+    <T> LifecycleEventType.@NonNull Prioritizable<BootstrapContext, ReloadableRegistrarEvent<PostFlattenTagRegistrar<T>>> postFlatten(@NonNull RegistryKey<T> registryKey);
++    <T> LifecycleEventType.Prioritizable<BootstrapContext, ReloadableRegistrarEvent<PostFlattenTagRegistrar<T>>> postFlatten(RegistryKey<T> registryKey);
 +}
 diff --git a/src/main/java/io/papermc/paper/tag/PostFlattenTagRegistrar.java b/src/main/java/io/papermc/paper/tag/PostFlattenTagRegistrar.java
 new file mode 100644
@@ -92,10 +93,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.tag.TagKey;
 +import java.util.Collection;
 +import java.util.Map;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Registrar for tags after they have been flattened. Flattened
@@ -110,7 +111,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * class YourBootstrapClass implements PluginBootstrap {
 + *
 + *     @Override
-+ *     public void bootstrap(@NotNull BootstrapContext context) {
++ *     public void bootstrap(BootstrapContext context) {
 + *         LifecycleEventManager<BootstrapContext> manager = context.getLifecycleManager();
 + *         manager.registerEventHandler(LifecycleEvents.TAGS.postFlatten(RegistryKey.ENCHANTMENT), event -> {
 + *             final PostFlattenTagRegistrar<Enchantment> registrar = event.registrar();
@@ -127,6 +128,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see PreFlattenTagRegistrar
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface PostFlattenTagRegistrar<T> extends Registrar {
 +
@@ -135,7 +137,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the registry key
 +     */
-+    @NonNull RegistryKey<T> registryKey();
++    RegistryKey<T> registryKey();
 +
 +    /**
 +     * Get a copy of all tags currently held in this registrar.
@@ -143,7 +145,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return an immutable map of all tags
 +     */
 +    @Contract(value = "-> new", pure = true)
-+    @Unmodifiable @NonNull Map<TagKey<T>, Collection<TypedKey<T>>> getAllTags();
++    @Unmodifiable Map<TagKey<T>, Collection<TypedKey<T>>> getAllTags();
 +
 +    /**
 +     * Checks if this registrar has a tag with the given key.
@@ -152,7 +154,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return true if the tag exists, false otherwise
 +     */
 +    @Contract(pure = true)
-+    boolean hasTag(@NonNull TagKey<T> tagKey);
++    boolean hasTag(TagKey<T> tagKey);
 +
 +    /**
 +     * Get the tag with the given key. Use {@link #hasTag(TagKey)} to check
@@ -164,7 +166,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see #hasTag(TagKey)
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    @Unmodifiable @NonNull Collection<TypedKey<T>> getTag(@NonNull TagKey<T> tagKey);
++    @Unmodifiable Collection<TypedKey<T>> getTag(TagKey<T> tagKey);
 +
 +    /**
 +     * Adds values to the given tag. If the tag does not exist, it will be created.
@@ -174,7 +176,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see #setTag(TagKey, Collection)
 +     */
 +    @Contract(mutates = "this")
-+    void addToTag(@NonNull TagKey<T> tagKey, @NonNull Collection<TypedKey<T>> values);
++    void addToTag(TagKey<T> tagKey, Collection<TypedKey<T>> values);
 +
 +    /**
 +     * Sets the values of the given tag. If the tag does not exist, it will be created.
@@ -185,7 +187,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see #addToTag(TagKey, Collection)
 +     */
 +    @Contract(mutates = "this")
-+    void setTag(@NonNull TagKey<T> tagKey, @NonNull Collection<TypedKey<T>> values);
++    void setTag(TagKey<T> tagKey, Collection<TypedKey<T>> values);
 +}
 diff --git a/src/main/java/io/papermc/paper/tag/PreFlattenTagRegistrar.java b/src/main/java/io/papermc/paper/tag/PreFlattenTagRegistrar.java
 new file mode 100644
@@ -201,10 +203,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import java.util.Collection;
 +import java.util.List;
 +import java.util.Map;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
 +import org.jetbrains.annotations.Unmodifiable;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Registrar for tags before they are flattened. Flattened
@@ -218,7 +220,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * class YourBootstrapClass implements PluginBootstrap {
 + *
 + *     @Override
-+ *     public void bootstrap(@NotNull BootstrapContext context) {
++ *     public void bootstrap(BootstrapContext context) {
 + *         LifecycleEventManager<BootstrapContext> manager = context.getLifecycleManager();
 + *         manager.registerEventHandler(LifecycleEvents.TAGS.preFlatten(RegistryKey.ITEM), event -> {
 + *             final PreFlattenTagRegistrar<ItemType> registrar = event.registrar();
@@ -235,6 +237,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see PostFlattenTagRegistrar
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface PreFlattenTagRegistrar<T> extends Registrar {
 +
@@ -243,7 +246,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the registry key
 +     */
-+    @NonNull RegistryKey<T> registryKey();
++    RegistryKey<T> registryKey();
 +
 +    /**
 +     * Get a copy of all tags currently held in this registrar.
@@ -251,7 +254,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return an immutable map of all tags
 +     */
 +    @Contract(value = "-> new", pure = true)
-+    @Unmodifiable @NonNull Map<TagKey<T>, Collection<TagEntry<T>>> getAllTags();
++    @Unmodifiable Map<TagKey<T>, Collection<TagEntry<T>>> getAllTags();
 +
 +    /**
 +     * Checks if this registrar has a tag with the given key.
@@ -260,7 +263,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return true if the tag exists, false otherwise
 +     */
 +    @Contract(pure = true)
-+    boolean hasTag(@NonNull TagKey<T> tagKey);
++    boolean hasTag(TagKey<T> tagKey);
 +
 +    /**
 +     * Get the tag with the given key. Use {@link #hasTag(TagKey)} to check
@@ -272,7 +275,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see #hasTag(TagKey)
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    @Unmodifiable @NonNull List<TagEntry<T>> getTag(@NonNull TagKey<T> tagKey);
++    @Unmodifiable List<TagEntry<T>> getTag(TagKey<T> tagKey);
 +
 +    /**
 +     * Adds entries to the given tag. If the tag does not exist, it will be created.
@@ -282,7 +285,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see #setTag(TagKey, Collection)
 +     */
 +    @Contract(mutates = "this")
-+    void addToTag(@NonNull TagKey<T> tagKey, @NonNull Collection<TagEntry<T>> entries);
++    void addToTag(TagKey<T> tagKey, Collection<TagEntry<T>> entries);
 +
 +    /**
 +     * Sets the entries of the given tag. If the tag does not exist, it will be created.
@@ -293,7 +296,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @see #addToTag(TagKey, Collection)
 +     */
 +    @Contract(mutates = "this")
-+    void setTag(@NonNull TagKey<T> tagKey, @NonNull Collection<TagEntry<T>> entries);
++    void setTag(TagKey<T> tagKey, Collection<TagEntry<T>> entries);
 +}
 diff --git a/src/main/java/io/papermc/paper/tag/TagEntry.java b/src/main/java/io/papermc/paper/tag/TagEntry.java
 new file mode 100644
@@ -306,9 +309,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.registry.TypedKey;
 +import io.papermc.paper.registry.tag.TagKey;
 +import net.kyori.adventure.key.Keyed;
-+import org.checkerframework.checker.nullness.qual.NonNull;
 +import org.jetbrains.annotations.ApiStatus;
 +import org.jetbrains.annotations.Contract;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * An entry is a pre-flattened tag. Represents
@@ -318,6 +321,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 + * @see PreFlattenTagRegistrar
 + */
 +@ApiStatus.Experimental
++@NullMarked
 +@ApiStatus.NonExtendable
 +public interface TagEntry<T> extends Keyed {
 +
@@ -329,7 +333,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the type of value
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    static <T> @NonNull TagEntry<T> valueEntry(final @NonNull TypedKey<T> entryKey) {
++    static <T> TagEntry<T> valueEntry(final TypedKey<T> entryKey) {
 +        return valueEntry(entryKey, true);
 +    }
 +
@@ -342,7 +346,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the type of value
 +     */
 +    @Contract(value = "_, _ -> new", pure = true)
-+    static <T> @NonNull TagEntry<T> valueEntry(final @NonNull TypedKey<T> entryKey, final boolean isRequired) {
++    static <T> TagEntry<T> valueEntry(final TypedKey<T> entryKey, final boolean isRequired) {
 +        return new TagEntryImpl<>(entryKey.key(), false, isRequired);
 +    }
 +
@@ -354,7 +358,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the type of value
 +     */
 +    @Contract(value = "_ -> new", pure = true)
-+    static <T> @NonNull TagEntry<T> tagEntry(final @NonNull TagKey<T> tagKey) {
++    static <T> TagEntry<T> tagEntry(final TagKey<T> tagKey) {
 +        return tagEntry(tagKey, true);
 +    }
 +
@@ -367,7 +371,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param <T> the type of value
 +     */
 +    @Contract(value = "_, _ -> new", pure = true)
-+    static <T> @NonNull TagEntry<T> tagEntry(final @NonNull TagKey<T> tagKey, final boolean isRequired) {
++    static <T> TagEntry<T> tagEntry(final TagKey<T> tagKey, final boolean isRequired) {
 +        return new TagEntryImpl<>(tagKey.key(), true, isRequired);
 +    }
 +
@@ -400,7 +404,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import net.kyori.adventure.key.Key;
 +import org.jetbrains.annotations.ApiStatus;
++import org.jspecify.annotations.NullMarked;
 +
++@NullMarked
 +@ApiStatus.Internal
 +record TagEntryImpl<T>(Key key, boolean isTag, boolean isRequired) implements TagEntry<T> {
 +}

patches/api/add-number-format-api.patch

@@ -26,11 +26,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import net.kyori.adventure.text.Component;
 +import net.kyori.adventure.text.ComponentLike;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A scoreboard number format that replaces the score number with a chat component.
 + */
++@NullMarked
 +public interface FixedFormat extends NumberFormat, ComponentLike {
 +
 +    /**
@@ -38,7 +39,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the chat component
 +     */
-+    @NotNull Component component();
++    Component component();
 +
 +}
 diff --git a/src/main/java/io/papermc/paper/scoreboard/numbers/FixedFormatImpl.java b/src/main/java/io/papermc/paper/scoreboard/numbers/FixedFormatImpl.java
@@ -50,12 +51,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.scoreboard.numbers;
 +
 +import net.kyori.adventure.text.Component;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
-+record FixedFormatImpl(@NotNull Component component) implements FixedFormat {
++@NullMarked
++record FixedFormatImpl(Component component) implements FixedFormat {
 +
 +    @Override
-+    public @NotNull Component asComponent() {
++    public Component asComponent() {
 +        return this.component();
 +    }
 +}
@@ -70,11 +72,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import net.kyori.adventure.text.ComponentLike;
 +import net.kyori.adventure.text.format.Style;
 +import net.kyori.adventure.text.format.StyleBuilderApplicable;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Describes a scoreboard number format that applies custom formatting to scoreboard scores.
 + */
++@NullMarked
 +public interface NumberFormat {
 +
 +    /**
@@ -82,7 +85,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return a blank number format
 +     */
-+    static @NotNull NumberFormat blank() {
++    static NumberFormat blank() {
 +        return BlankFormatImpl.INSTANCE;
 +    }
 +
@@ -91,7 +94,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return an un-styled number format
 +     */
-+    static @NotNull StyledFormat noStyle() {
++    static StyledFormat noStyle() {
 +        return StyledFormatImpl.NO_STYLE;
 +    }
 +
@@ -101,7 +104,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param style the style to apply on the number
 +     * @return a styled number format
 +     */
-+    static @NotNull StyledFormat styled(final @NotNull Style style) {
++    static StyledFormat styled(final Style style) {
 +        return new StyledFormatImpl(style);
 +    }
 +
@@ -111,7 +114,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param styleBuilderApplicables the style to apply on the number
 +     * @return a styled number format
 +     */
-+    static @NotNull StyledFormat styled(final @NotNull StyleBuilderApplicable @NotNull... styleBuilderApplicables) {
++    static StyledFormat styled(final StyleBuilderApplicable... styleBuilderApplicables) {
 +        return styled(Style.style(styleBuilderApplicables));
 +    }
 +
@@ -121,7 +124,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param component the component to replace the number with
 +     * @return a fixed number format
 +     */
-+    static @NotNull FixedFormat fixed(final @NotNull ComponentLike component) {
++    static FixedFormat fixed(final ComponentLike component) {
 +        return new FixedFormatImpl(component.asComponent());
 +    }
 +}
@@ -135,11 +138,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import net.kyori.adventure.text.format.Style;
 +import net.kyori.adventure.text.format.StyleBuilderApplicable;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * A scoreboard number format that applies a custom formatting to the score number.
 + */
++@NullMarked
 +public interface StyledFormat extends NumberFormat, StyleBuilderApplicable {
 +
 +    /**
@@ -147,7 +151,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the style to apply
 +     */
-+    @NotNull Style style();
++    Style style();
 +
 +}
 diff --git a/src/main/java/io/papermc/paper/scoreboard/numbers/StyledFormatImpl.java b/src/main/java/io/papermc/paper/scoreboard/numbers/StyledFormatImpl.java
@@ -159,13 +163,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.scoreboard.numbers;
 +
 +import net.kyori.adventure.text.format.Style;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
-+record StyledFormatImpl(@NotNull Style style) implements StyledFormat {
++@NullMarked
++record StyledFormatImpl(Style style) implements StyledFormat {
 +    static final StyledFormat NO_STYLE = new StyledFormatImpl(Style.empty());
 +
 +    @Override
-+    public void styleApply(final Style.@NotNull Builder style) {
++    public void styleApply(final Style.Builder style) {
 +        style.merge(this.style);
 +    }
 +}

patches/api/create-TileStateInventoryHolder.patch

@@ -16,11 +16,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.block.TileState;
 +import org.bukkit.inventory.BlockInventoryHolder;
 +import org.bukkit.inventory.Inventory;
-+import org.checkerframework.checker.nullness.qual.NonNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents a {@link TileState} block that has an inventory.
 + */
++@NullMarked
 +public interface TileStateInventoryHolder extends TileState, BlockInventoryHolder {
 +
 +    /**
@@ -35,7 +36,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return the inventory
 +     */
 +    @Override
-+    @NonNull Inventory getInventory();
++    Inventory getInventory();
 +
 +    /**
 +     * Gets the captured inventory snapshot of this container.
@@ -47,7 +48,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the captured inventory snapshot
 +     */
-+    @NonNull Inventory getSnapshotInventory();
++    Inventory getSnapshotInventory();
 +}
 diff --git a/src/main/java/org/bukkit/block/ChiseledBookshelf.java b/src/main/java/org/bukkit/block/ChiseledBookshelf.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644

patches/api/improve-BanList-types.patch

@@ -15,12 +15,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import org.bukkit.BanList;
 +import org.bukkit.ban.IpBanList;
 +import org.bukkit.ban.ProfileBanList;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +/**
 + * Represents a ban-type that a {@link BanList} may track.
 + * It enforces the correct return value at compile time.
 + */
++@NullMarked
 +public interface BanListType<T> {
 +
 +    /**
@@ -37,7 +38,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     *
 +     * @return the type class
 +     */
-+    @NotNull Class<T> typeClass();
++    Class<T> typeClass();
 +}
 diff --git a/src/main/java/io/papermc/paper/ban/BanListTypeImpl.java b/src/main/java/io/papermc/paper/ban/BanListTypeImpl.java
 new file mode 100644
@@ -48,10 +49,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +package io.papermc.paper.ban;
 +
 +import org.jetbrains.annotations.ApiStatus;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
 +
 +@ApiStatus.Internal
-+record BanListTypeImpl<T>(@NotNull Class<T> typeClass) implements BanListType<T> {
++@NullMarked
++record BanListTypeImpl<T>(Class<T> typeClass) implements BanListType<T> {
 +}
 diff --git a/src/main/java/org/bukkit/BanList.java b/src/main/java/org/bukkit/BanList.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644

patches/server/Brigadier-based-command-API.patch

@@ -1053,13 +1053,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +import com.mojang.brigadier.context.CommandContext;
 +import com.mojang.brigadier.exceptions.CommandSyntaxException;
++import java.util.concurrent.CompletableFuture;
 +import net.kyori.adventure.chat.SignedMessage;
 +import net.minecraft.commands.CommandSourceStack;
 +import net.minecraft.commands.arguments.MessageArgument;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+
-+import java.util.concurrent.CompletableFuture;
 +
++@NullMarked
 +public record SignedMessageResolverImpl(MessageArgument.Message message) implements SignedMessageResolver {
 +
 +    @Override
@@ -1067,13 +1067,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        return this.message.text();
 +    }
 +
++    @SuppressWarnings({"rawtypes", "unchecked"})
 +    @Override
-+    public @NotNull CompletableFuture<SignedMessage> resolveSignedMessage(final String argumentName, final CommandContext erased) throws CommandSyntaxException {
++    public CompletableFuture<SignedMessage> resolveSignedMessage(final String argumentName, final CommandContext erased) throws CommandSyntaxException {
-+        final CommandContext<CommandSourceStack> type = erased;
 +        final CompletableFuture<SignedMessage> future = new CompletableFuture<>();
 +
-+        final MessageArgument.Message response = type.getArgument(argumentName, SignedMessageResolverImpl.class).message;
++        final MessageArgument.Message response = ((CommandContext<CommandSourceStack>) erased).getArgument(argumentName, SignedMessageResolverImpl.class).message;
-+        MessageArgument.resolveChatMessage(response, type, argumentName, (message) -> {
++        MessageArgument.resolveChatMessage(response, erased, argumentName, (message) -> {
 +            future.complete(message.adventureView());
 +        });
 +        return future;

patches/server/More-CommandBlock-API.patch

@@ -16,31 +16,32 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +import io.papermc.paper.command.CommandBlockHolder;
 +import net.kyori.adventure.text.Component;
 +import net.minecraft.world.level.BaseCommandBlock;
-+import org.jetbrains.annotations.NotNull;
++import org.jspecify.annotations.NullMarked;
-+import org.jetbrains.annotations.Nullable;
++import org.jspecify.annotations.Nullable;
 +
++@NullMarked
 +public interface PaperCommandBlockHolder extends CommandBlockHolder {
 +
 +    BaseCommandBlock getCommandBlockHandle();
 +
 +    @Override
-+    default @NotNull Component lastOutput() {
++    default Component lastOutput() {
-+        return PaperAdventure.asAdventure(getCommandBlockHandle().getLastOutput());
++        return PaperAdventure.asAdventure(this.getCommandBlockHandle().getLastOutput());
 +    }
 +
 +    @Override
-+    default void lastOutput(@Nullable Component lastOutput) {
++    default void lastOutput(final @Nullable Component lastOutput) {
-+        getCommandBlockHandle().setLastOutput(PaperAdventure.asVanilla(lastOutput));
++        this.getCommandBlockHandle().setLastOutput(PaperAdventure.asVanilla(lastOutput));
 +    }
 +
 +    @Override
 +    default int getSuccessCount() {
-+        return getCommandBlockHandle().getSuccessCount();
++        return this.getCommandBlockHandle().getSuccessCount();
 +    }
 +
 +    @Override
-+    default void setSuccessCount(int successCount) {
++    default void setSuccessCount(final int successCount) {
-+        getCommandBlockHandle().setSuccessCount(successCount);
++        this.getCommandBlockHandle().setSuccessCount(successCount);
 +    }
 +}
 diff --git a/src/main/java/org/bukkit/craftbukkit/block/CraftCommandBlock.java b/src/main/java/org/bukkit/craftbukkit/block/CraftCommandBlock.java

test-plugin/src/main/java/io/papermc/testplugin/brigtests/Registration.java

@@ -98,12 +98,12 @@ public final class Registration {
 
             commands.register(plugin.getPluginMeta(), "example", "test", Collections.emptyList(), new BasicCommand() {
                 @Override
-                public void execute(@NotNull final CommandSourceStack commandSourceStack, final @NotNull String[] args) {
+                public void execute(@NotNull final CommandSourceStack commandSourceStack, final @NotNull String @NotNull [] args) {
                     System.out.println(Arrays.toString(args));
                 }
 
                 @Override
-                public @NotNull Collection<String> suggest(final @NotNull CommandSourceStack commandSourceStack, final @NotNull String[] args) {
+                public @NotNull Collection<String> suggest(final @NotNull CommandSourceStack commandSourceStack, final @NotNull String @NotNull [] args) {
                     System.out.println(Arrays.toString(args));
                     return List.of("apple", "banana");
                 }