From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sat, 27 Apr 2024 20:56:17 -0700
Subject: [PATCH] General ItemMeta fixes

== AT ==
private-f net/minecraft/world/item/ItemStack components

diff --git a/src/main/java/net/minecraft/world/item/ItemStack.java b/src/main/java/net/minecraft/world/item/ItemStack.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/item/ItemStack.java
+++ b/src/main/java/net/minecraft/world/item/ItemStack.java
@@ -0,0 +0,0 @@ public final class ItemStack implements DataComponentHolder {
             } finally {
                 world.captureBlockStates = false;
             }
-            DataComponentPatch newData = this.getComponentsPatch();
+            DataComponentPatch newData = this.components.asPatch(); // Paper - Directly access components as patch instead of getComponentsPatch as said method yields EMPTY on items with count 0
             int newCount = this.getCount();
             this.setCount(oldCount);
             this.restorePatch(oldData);
@@ -0,0 +0,0 @@ public final class ItemStack implements DataComponentHolder {
     public void setItem(Item item) {
         this.bukkitStack = null; // Paper
         this.item = item;
+        // Paper start - change base component prototype
+        final DataComponentPatch patch = this.getComponentsPatch();
+        this.components = new PatchedDataComponentMap(this.item.components());
+        this.applyComponents(patch);
+        // Paper end - change base component prototype
     }
     // CraftBukkit end
 
diff --git a/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
+++ b/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
@@ -0,0 +0,0 @@ public abstract class BlockEntity {
         CompoundTag nbttagcompound = new CompoundTag();
 
         this.saveAdditional(nbttagcompound, registryLookup);
+        // Paper start - store PDC here as well
+        if (this.persistentDataContainer != null && !this.persistentDataContainer.isEmpty()) {
+            nbttagcompound.put("PublicBukkitValues", this.persistentDataContainer.toTagCompound());
+        }
+        // Paper end
         return nbttagcompound;
     }
 
diff --git a/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java b/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java
+++ b/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java
@@ -0,0 +0,0 @@ public abstract class CraftBlockEntityState<T extends BlockEntity> extends Craft
         return nbt;
     }
 
+    // Paper start - properly save blockentity itemstacks
+    public CompoundTag getSnapshotCustomNbtOnly() {
+        this.applyTo(this.snapshot);
+        final CompoundTag nbt = this.snapshot.saveCustomOnly(this.getRegistryAccess());
+        this.snapshot.removeComponentsFromTag(nbt);
+        return nbt;
+    }
+    // Paper end
+
     // copies the data of the given tile entity to this block state
     protected void load(T tileEntity) {
         if (tileEntity != null && tileEntity != this.snapshot) {
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
@@ -0,0 +0,0 @@ public final class CraftItemStack extends ItemStack {
     // Paper end - improve handled tags on type change
     // Paper start
     public static void applyMetaToItem(net.minecraft.world.item.ItemStack itemStack, ItemMeta itemMeta) {
-        final CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator();
+        // Paper start - support updating profile after resolving it
+        final CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator() {
+            @Override
+            void skullCallback(final com.mojang.authlib.GameProfile gameProfile) {
+                itemStack.set(DataComponents.PROFILE, new net.minecraft.world.item.component.ResolvableProfile(gameProfile));
+            }
+        };
+        // Paper end - support updating profile after resolving it
         ((CraftMetaItem) itemMeta).applyToItem(tag);
         itemStack.applyComponents(tag.build());
     }
@@ -0,0 +0,0 @@ public final class CraftItemStack extends ItemStack {
         }
 
         if (!((CraftMetaItem) itemMeta).isEmpty()) {
-            CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator();
+            // Paper start - support updating profile after resolving it
+            CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator() {
+                @Override
+                void skullCallback(final com.mojang.authlib.GameProfile gameProfile) {
+                    item.set(DataComponents.PROFILE, new net.minecraft.world.item.component.ResolvableProfile(gameProfile));
+                }
+            };
+            // Paper end - support updating profile after resolving it
 
             ((CraftMetaItem) itemMeta).applyToItem(tag);
             item.restorePatch(tag.build());
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBanner.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBanner.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBanner.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBanner.java
@@ -0,0 +0,0 @@ public class CraftMetaBanner extends CraftMetaItem implements BannerMeta {
     void applyToItem(CraftMetaItem.Applicator tag) {
         super.applyToItem(tag);
 
+        if (this.patterns.isEmpty()) return; // Paper - don't write empty patterns
         List<BannerPatternLayers.Layer> newPatterns = new ArrayList<>();
 
         for (Pattern p : this.patterns) {
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java
@@ -0,0 +0,0 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
         super.applyToItem(tag);
 
         if (this.blockEntityTag != null) {
-            tag.put(CraftMetaBlockState.BLOCK_ENTITY_TAG, CustomData.of(this.blockEntityTag.getSnapshotNBTWithoutComponents()));
+            // Paper start - accurately replicate logic for creating ItemStack from BlockEntity
+            // taken from BlockEntity#saveToItem and BlockItem#setBlockEntityData
+            CompoundTag nbt = this.blockEntityTag.getSnapshotCustomNbtOnly();
+            nbt.remove("id");
+            if (!nbt.isEmpty()) {
+                BlockEntity.addEntityType(nbt, this.blockEntityTag.getTileEntity().getType());
+                tag.put(CraftMetaBlockState.BLOCK_ENTITY_TAG, CustomData.of(nbt));
+            }
+            // Paper end
 
             for (TypedDataComponent<?> component : this.blockEntityTag.collectComponents()) {
-                tag.putIfAbsent(component);
+                if (CraftMetaItem.DEFAULT_HANDLED_DCTS.contains(component.type())) continue; // Paper - if the component type was already handled by CraftMetaItem, don't add it again
+                tag.builder.set(component);
             }
         }
     }
@@ -0,0 +0,0 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
         Preconditions.checkArgument(blockStateType == blockState.getClass() && blockState instanceof CraftBlockEntityState, "Invalid blockState for " + this.material);
 
         this.blockEntityTag = (CraftBlockEntityState<?>) blockState;
+        // Paper start - when a new BlockState is set, the components from that block entity
+        // have to be used to update the fields on CraftMetaItem
+        final PatchedDataComponentMap patchedMap = new net.minecraft.core.component.PatchedDataComponentMap(this.blockEntityTag.getHandle().getBlock().asItem().components());
+        final net.minecraft.core.component.DataComponentMap map = this.blockEntityTag.collectComponents();
+        patchedMap.setAll(map);
+        this.updateFromPatch(patchedMap.asPatch(), null);
+        // Paper end
     }
 
     private static Material shieldToBannerHack() {
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBookSigned.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBookSigned.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBookSigned.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBookSigned.java
@@ -0,0 +0,0 @@ public class CraftMetaBookSigned extends CraftMetaItem implements BookMeta {
             }
         }
 
-        this.resolved = SerializableMeta.getObject(Boolean.class, map, CraftMetaBookSigned.RESOLVED.BUKKIT, true);
-        this.generation = SerializableMeta.getObject(Integer.class, map, CraftMetaBookSigned.GENERATION.BUKKIT, true);
+        this.resolved = SerializableMeta.getBoolean(map, CraftMetaBookSigned.RESOLVED.BUKKIT); // Paper - General ItemMeta fixes
+        this.generation = SerializableMeta.getObjectOptionally(Integer.class, map, CraftMetaBookSigned.GENERATION.BUKKIT, true).orElse(0); // Paper - General ItemMeta Fixes
     }
 
     @Override
@@ -0,0 +0,0 @@ public class CraftMetaBookSigned extends CraftMetaItem implements BookMeta {
             for (Component page : this.pages) {
                 list.add(Filterable.passThrough(page));
             }
-            itemData.put(CraftMetaBookSigned.BOOK_CONTENT, new WrittenBookContent(Filterable.from(FilteredText.passThrough(this.title)), this.author, this.generation, list, this.resolved));
+            itemData.put(CraftMetaBookSigned.BOOK_CONTENT, new WrittenBookContent(Filterable.from(FilteredText.passThrough(this.title == null ? "" : this.title)), this.author == null ? "" : this.author, this.generation, list, this.resolved));
         }
     }
 
@@ -0,0 +0,0 @@ public class CraftMetaBookSigned extends CraftMetaItem implements BookMeta {
         }
 
         if (this.pages != null) {
-            builder.put(CraftMetaBookSigned.BOOK_PAGES.BUKKIT, ImmutableList.copyOf(this.pages));
+            // Paper start - deserialization expects json
+            final List<String> jsonPages = new ArrayList<>(this.pages.size());
+            for (final Component page : this.pages) {
+                jsonPages.add(CraftChatMessage.toJSON(page));
+            }
+            builder.put(CraftMetaBookSigned.BOOK_PAGES.BUKKIT, ImmutableList.copyOf(jsonPages));
+            // Paper end - deserialization expects json
         }
 
         if (this.resolved) {
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaCompass.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaCompass.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaCompass.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaCompass.java
@@ -0,0 +0,0 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
     private int lodestoneX;
     private int lodestoneY;
     private int lodestoneZ;
-    private boolean tracked = true;
+    private Boolean tracked = null; // Paper - tri-state
 
     CraftMetaCompass(CraftMetaItem meta) {
         super(meta);
@@ -0,0 +0,0 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
                 this.setLodestone(lodestone);
             }
         }
-        this.tracked = SerializableMeta.getBoolean(map, CraftMetaCompass.LODESTONE_TRACKED.BUKKIT);
+        this.tracked = SerializableMeta.getObjectOptionally(Boolean.class, map, CraftMetaCompass.LODESTONE_TRACKED.BUKKIT, true).orElse(null); // Paper - tri-state
     }
 
     @Override
@@ -0,0 +0,0 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
     }
 
     boolean hasLodestoneTracked() {
-        return !this.tracked;
+        return this.tracked != null; // Paper - tri-state
     }
 
     @Override
     public boolean isLodestoneTracked() {
-        return this.tracked;
+        return this.tracked != null && this.tracked; // Paper - tri-state
     }
 
     @Override
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaFirework.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaFirework.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaFirework.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaFirework.java
@@ -0,0 +0,0 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
         }
 
         Iterable<?> effects = SerializableMeta.getObject(Iterable.class, map, CraftMetaFirework.EXPLOSIONS.BUKKIT, true);
-        this.safelyAddEffects(effects);
+        this.safelyAddEffects(effects, false); // Paper - limit firework effects
     }
 
     @Override
@@ -0,0 +0,0 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
         return !(this.effects == null || this.effects.isEmpty());
     }
 
-    void safelyAddEffects(Iterable<?> collection) {
+    void safelyAddEffects(Iterable<?> collection, final boolean throwOnOversize) { // Paper
         if (collection == null || (collection instanceof Collection && ((Collection<?>) collection).isEmpty())) {
             return;
         }
@@ -0,0 +0,0 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
 
         for (Object obj : collection) {
             Preconditions.checkArgument(obj instanceof FireworkEffect, "%s in %s is not a FireworkEffect", obj, collection);
+            // Paper start - limit firework effects
+            if (effects.size() + 1 > Fireworks.MAX_EXPLOSIONS) {
+                if (throwOnOversize) {
+                    throw new IllegalArgumentException("Cannot have more than " + Fireworks.MAX_EXPLOSIONS + " firework effects");
+                } else {
+                    continue;
+                }
+            }
+            // Paper end - limit firework effects
             effects.add((FireworkEffect) obj);
         }
     }
@@ -0,0 +0,0 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
         }
 
         List<FireworkExplosion> effects = new ArrayList<>();
-        for (FireworkEffect effect : this.effects) {
-            effects.add(CraftMetaFirework.getExplosion(effect));
+        // Paper start - fix NPE with effects list being null
+        if (this.effects != null) {
+            for (FireworkEffect effect : this.effects) {
+                effects.add(CraftMetaFirework.getExplosion(effect));
+            }
         }
+        // Paper end
 
         itemTag.put(CraftMetaFirework.FIREWORKS, new Fireworks(this.power, effects));
     }
@@ -0,0 +0,0 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
     @Override
     public void addEffect(FireworkEffect effect) {
         Preconditions.checkArgument(effect != null, "FireworkEffect cannot be null");
+        Preconditions.checkArgument(this.effects == null || this.effects.size() + 1 <= Fireworks.MAX_EXPLOSIONS, "cannot have more than %s firework effects", Fireworks.MAX_EXPLOSIONS); // Paper - limit firework effects
         if (this.effects == null) {
             this.effects = new ArrayList<FireworkEffect>();
         }
@@ -0,0 +0,0 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
     @Override
     public void addEffects(FireworkEffect... effects) {
         Preconditions.checkArgument(effects != null, "effects cannot be null");
+        // Paper start - limit firework effects
+        final int initialSize = this.effects == null ? 0 : this.effects.size();
+        Preconditions.checkArgument(initialSize + effects.length <= Fireworks.MAX_EXPLOSIONS, "Cannot have more than %s firework effects", Fireworks.MAX_EXPLOSIONS);
+        // Paper end - limit firework effects
         if (effects.length == 0) {
             return;
         }
@@ -0,0 +0,0 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
     @Override
     public void addEffects(Iterable<FireworkEffect> effects) {
         Preconditions.checkArgument(effects != null, "effects cannot be null");
-        this.safelyAddEffects(effects);
+        this.safelyAddEffects(effects, true); // Paper - limit firework effects
     }
 
     @Override
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaItem.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaItem.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaItem.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaItem.java
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
         }
     }
 
-    static final class Applicator {
+    static abstract class Applicator { // Paper - support updating profile after resolving it
 
-        private final DataComponentPatch.Builder builder = DataComponentPatch.builder();
+        final DataComponentPatch.Builder builder = DataComponentPatch.builder(); // Paper - private -> package-private
+        void skullCallback(com.mojang.authlib.GameProfile gameProfile) {} // Paper - support updating profile after resolving it
 
         <T> Applicator put(ItemMetaKeyType<T> key, T value) {
             this.builder.set(key.TYPE, value);
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
             this.enchantments = new EnchantmentMap(meta.enchantments); // Paper
         }
 
-        if (meta.hasAttributeModifiers()) {
+        if (meta.attributeModifiers != null) { // Paper
             this.attributeModifiers = LinkedHashMultimap.create(meta.attributeModifiers);
         }
 
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     }
 
     CraftMetaItem(DataComponentPatch tag, Set<DataComponentType<?>> extraHandledTags) { // Paper - improve handled tags on type changes
+        // Paper start - properly support data components in BlockEntity
+        this.updateFromPatch(tag, extraHandledTags);
+    }
+    protected final void updateFromPatch(DataComponentPatch tag, Set<DataComponentType<?>> extraHandledTags) {
+        // Paper end - properly support data components in BlockEntity
         CraftMetaItem.getOrEmpty(tag, CraftMetaItem.NAME).ifPresent((component) -> {
             this.displayName = component;
         });
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
         Map<?, ?> mods = SerializableMeta.getObject(Map.class, map, key.BUKKIT, true);
         Multimap<Attribute, AttributeModifier> result = LinkedHashMultimap.create();
         if (mods == null) {
-            return result;
+            return null; // Paper - null is different from an empty map
         }
 
         for (Object obj : mods.keySet()) {
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     }
 
     void applyModifiers(Multimap<Attribute, AttributeModifier> modifiers, CraftMetaItem.Applicator tag) {
-        if (modifiers == null || modifiers.isEmpty()) {
-            if (this.hasItemFlag(ItemFlag.HIDE_ATTRIBUTES)) {
-                tag.put(CraftMetaItem.ATTRIBUTES, new ItemAttributeModifiers(Collections.emptyList(), false));
-            }
+        if (modifiers == null/* || modifiers.isEmpty()*/) { // Paper - empty modifiers has a specific meaning, they should still be saved
+            // Paper - don't save ItemFlag if the underlying data isn't present
             return;
         }
 
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Overridden
     boolean isEmpty() {
-        return !(this.hasDisplayName() || this.hasItemName() || this.hasLocalizedName() || this.hasEnchants() || (this.lore != null) || this.hasCustomModelData() || this.hasBlockData() || this.hasRepairCost() || !this.unhandledTags.build().isEmpty() || !this.persistentDataContainer.isEmpty() || this.hideFlag != 0 || this.isHideTooltip() || this.isUnbreakable() || this.hasEnchantmentGlintOverride() || this.isFireResistant() || this.hasMaxStackSize() || this.hasRarity() || this.hasFood() || this.hasDamage() || this.hasMaxDamage() || this.hasAttributeModifiers() || this.customTag != null || this.canPlaceOnPredicates != null || this.canBreakPredicates != null); // Paper
+        return !(this.hasDisplayName() || this.hasItemName() || this.hasLocalizedName() || this.hasEnchants() || (this.lore != null) || this.hasCustomModelData() || this.hasBlockData() || this.hasRepairCost() || !this.unhandledTags.build().isEmpty() || !this.persistentDataContainer.isEmpty() || this.hideFlag != 0 || this.isHideTooltip() || this.isUnbreakable() || this.hasEnchantmentGlintOverride() || this.isFireResistant() || this.hasMaxStackSize() || this.hasRarity() || this.hasFood() || this.hasDamage() || this.hasMaxDamage() || this.attributeModifiers != null || this.customTag != null || this.canPlaceOnPredicates != null || this.canBreakPredicates != null); // Paper
     }
 
     // Paper start
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public void lore(final List<? extends net.kyori.adventure.text.Component> lore) {
+        Preconditions.checkArgument(lore == null || lore.size() <= ItemLore.MAX_LINES, "lore cannot have more than %s lines", ItemLore.MAX_LINES); // Paper - limit lore lines
         this.lore = lore != null ? io.papermc.paper.adventure.PaperAdventure.asVanilla(lore) : null;
     }
     // Paper end
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     // Paper end
     @Override
     public void setLore(List<String> lore) {
+        Preconditions.checkArgument(lore == null || lore.size() <= ItemLore.MAX_LINES, "lore cannot have more than %s lines", ItemLore.MAX_LINES); // Paper - limit lore lines
         if (lore == null || lore.isEmpty()) {
             this.lore = null;
         } else {
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     // Paper start
     @Override
     public void setLoreComponents(List<net.md_5.bungee.api.chat.BaseComponent[]> lore) {
+        Preconditions.checkArgument(lore == null || lore.size() <= ItemLore.MAX_LINES, "lore cannot have more than %s lines", ItemLore.MAX_LINES); // Paper - limit lore lines
         if (lore == null) {
             this.lore = null;
         } else {
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public String getAsString() {
-        CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator();
+        CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator() {}; // Paper - support updating profile after resolving it
         this.applyToItem(tag);
         DataComponentPatch patch = tag.build();
         Tag nbt = DataComponentPatch.CODEC.encodeStart(MinecraftServer.getDefaultRegistryAccess().createSerializationContext(NbtOps.INSTANCE), patch).getOrThrow();
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public String getAsComponentString() {
-        CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator();
+        CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator() {}; // Paper
         this.applyToItem(tag);
         DataComponentPatch patch = tag.build();
 
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
         if (first == null || second == null) {
             return false;
         }
+        if (first.isEmpty() && second.isEmpty()) return true; // Paper - empty modifiers are equivalent
         for (Map.Entry<Attribute, AttributeModifier> entry : first.entries()) {
             if (!second.containsEntry(entry.getKey(), entry.getValue())) {
                 return false;
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
                 && (this.hasCustomModelData() ? that.hasCustomModelData() && this.customModelData.equals(that.customModelData) : !that.hasCustomModelData())
                 && (this.hasBlockData() ? that.hasBlockData() && this.blockData.equals(that.blockData) : !that.hasBlockData())
                 && (this.hasRepairCost() ? that.hasRepairCost() && this.repairCost == that.repairCost : !that.hasRepairCost())
-                && (this.hasAttributeModifiers() ? that.hasAttributeModifiers() && CraftMetaItem.compareModifiers(this.attributeModifiers, that.attributeModifiers) : !that.hasAttributeModifiers())
+                && (this.attributeModifiers != null ? that.attributeModifiers != null && CraftMetaItem.compareModifiers(this.attributeModifiers, that.attributeModifiers) : that.attributeModifiers == null) // Paper - track only null modifiers
                 && (this.unhandledTags.equals(that.unhandledTags))
                 && (Objects.equals(this.customTag, that.customTag))
                 && (this.persistentDataContainer.equals(that.persistentDataContainer))
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
         hash = 61 * hash + (this.hasFood() ? this.food.hashCode() : 0);
         hash = 61 * hash + (this.hasDamage() ? this.damage : 0);
         hash = 61 * hash + (this.hasMaxDamage() ? 1231 : 1237);
-        hash = 61 * hash + (this.hasAttributeModifiers() ? this.attributeModifiers.hashCode() : 0);
+        hash = 61 * hash + (this.attributeModifiers != null ? this.attributeModifiers.hashCode() : 0); // Paper - track only null attributes
         hash = 61 * hash + (this.canPlaceOnPredicates != null ? this.canPlaceOnPredicates.hashCode() : 0); // Paper
         hash = 61 * hash + (this.canBreakPredicates != null ? this.canBreakPredicates.hashCode() : 0); // Paper
         hash = 61 * hash + this.version;
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
             if (this.enchantments != null) {
                 clone.enchantments = new EnchantmentMap(this.enchantments); // Paper
             }
-            if (this.hasAttributeModifiers()) {
+            if (this.attributeModifiers != null) { // Paper
                 clone.attributeModifiers = LinkedHashMultimap.create(this.attributeModifiers);
             }
             if (this.customTag != null) {
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     }
 
     static void serializeModifiers(Multimap<Attribute, AttributeModifier> modifiers, ImmutableMap.Builder<String, Object> builder, ItemMetaKey key) {
-        if (modifiers == null || modifiers.isEmpty()) {
+        if (modifiers == null/* || modifiers.isEmpty()*/) { // Paper - null and an empty map have different behaviors
             return;
         }
 
@@ -0,0 +0,0 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     // Paper start - improve checking handled tags
     @org.jetbrains.annotations.VisibleForTesting
     public static final Map<Class<? extends CraftMetaItem>, Set<DataComponentType<?>>> HANDLED_DCTS_PER_TYPE = new HashMap<>();
-    private static final Set<DataComponentType<?>> DEFAULT_HANDLED_DCTS = Set.of(
+    protected static final Set<DataComponentType<?>> DEFAULT_HANDLED_DCTS = Set.of(
         CraftMetaItem.NAME.TYPE,
         CraftMetaItem.ITEM_NAME.TYPE,
         CraftMetaItem.LORE.TYPE,
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaSkull.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaSkull.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaSkull.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaSkull.java
@@ -0,0 +0,0 @@ class CraftMetaSkull extends CraftMetaItem implements SkullMeta {
             // Fill in textures
             PlayerProfile ownerProfile = new CraftPlayerProfile(this.profile); // getOwnerProfile may return null
             if (ownerProfile.getTextures().isEmpty()) {
-                ownerProfile.update().thenAccept((filledProfile) -> {
+                ownerProfile.update().thenAcceptAsync((filledProfile) -> { // Paper - run on main thread
                     this.setOwnerProfile(filledProfile);
-                    tag.put(CraftMetaSkull.SKULL_PROFILE, new ResolvableProfile(this.profile));
-                });
+                    tag.skullCallback(this.profile); // Paper - actually set profile on itemstack
+                }, ((org.bukkit.craftbukkit.CraftServer) org.bukkit.Bukkit.getServer()).getServer()); // Paper - run on main thread
             }
         }
 
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/SerializableMeta.java b/src/main/java/org/bukkit/craftbukkit/inventory/SerializableMeta.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/SerializableMeta.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/SerializableMeta.java
@@ -0,0 +0,0 @@ public final class SerializableMeta implements ConfigurationSerializable {
         }
         throw new IllegalArgumentException(field + "(" + object + ") is not a valid " + clazz);
     }
+
+    // Paper start - General ItemMeta Fixes
+    public static <T> java.util.Optional<T> getObjectOptionally(Class<T> clazz, Map<?, ?> map, Object field, boolean nullable) {
+        final Object object = map.get(field);
+
+        if (clazz.isInstance(object)) {
+            return java.util.Optional.of(clazz.cast(object));
+        }
+        if (object == null) {
+            if (!nullable) {
+                throw new NoSuchElementException(map + " does not contain " + field);
+            }
+            return java.util.Optional.empty();
+        }
+        throw new IllegalArgumentException(field + "(" + object + ") is not a valid " + clazz);
+    }
+    // Paper end - General ItemMeta Fixes
 }
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/components/CraftFoodComponent.java b/src/main/java/org/bukkit/craftbukkit/inventory/components/CraftFoodComponent.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/components/CraftFoodComponent.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/components/CraftFoodComponent.java
@@ -0,0 +0,0 @@ public final class CraftFoodComponent implements FoodComponent {
 
     @Override
     public void setEatSeconds(float eatSeconds) {
+        Preconditions.checkArgument(eatSeconds > 0, "Eat seconds must be positive"); // Paper - validate eat_seconds
         this.handle = new FoodProperties(this.handle.nutrition(), this.handle.saturation(), this.handle.canAlwaysEat(), eatSeconds, this.handle.effects());
     }
 
diff --git a/src/test/java/org/bukkit/craftbukkit/inventory/DeprecatedItemMetaCustomValueTest.java b/src/test/java/org/bukkit/craftbukkit/inventory/DeprecatedItemMetaCustomValueTest.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/test/java/org/bukkit/craftbukkit/inventory/DeprecatedItemMetaCustomValueTest.java
+++ b/src/test/java/org/bukkit/craftbukkit/inventory/DeprecatedItemMetaCustomValueTest.java
@@ -0,0 +0,0 @@ public class DeprecatedItemMetaCustomValueTest extends AbstractTestingBase {
     public void testNBTTagStoring() {
         CraftMetaItem itemMeta = this.createComplexItemMeta();
 
-        CraftMetaItem.Applicator compound = new CraftMetaItem.Applicator();
+        CraftMetaItem.Applicator compound = new CraftMetaItem.Applicator() {}; // Paper
         itemMeta.applyToItem(compound);
 
         assertEquals(itemMeta, new CraftMetaItem(compound.build(), null)); // Paper
diff --git a/src/test/java/org/bukkit/craftbukkit/inventory/PersistentDataContainerTest.java b/src/test/java/org/bukkit/craftbukkit/inventory/PersistentDataContainerTest.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/test/java/org/bukkit/craftbukkit/inventory/PersistentDataContainerTest.java
+++ b/src/test/java/org/bukkit/craftbukkit/inventory/PersistentDataContainerTest.java
@@ -0,0 +0,0 @@ public class PersistentDataContainerTest extends AbstractTestingBase {
     public void testNBTTagStoring() {
         CraftMetaItem itemMeta = this.createComplexItemMeta();
 
-        CraftMetaItem.Applicator compound = new CraftMetaItem.Applicator();
+        CraftMetaItem.Applicator compound = new CraftMetaItem.Applicator() {}; // Paper
         itemMeta.applyToItem(compound);
 
         assertEquals(itemMeta, new CraftMetaItem(compound.build(), null)); // Paper
@@ -0,0 +0,0 @@ public class PersistentDataContainerTest extends AbstractTestingBase {
         assertEquals(List.of(), container.get(PersistentDataContainerTest.requestKey("list"), PersistentDataType.LIST.strings()));
 
         // Write and read the entire container to NBT
-        final CraftMetaItem.Applicator storage = new CraftMetaItem.Applicator();
+        final CraftMetaItem.Applicator storage = new CraftMetaItem.Applicator() {}; // Paper
         craftItem.applyToItem(storage);
 
         final CraftMetaItem readItem = new CraftMetaItem(storage.build(), null); // Paper
