Clone mutable types in events when changes are discarded (#10333)

patches/api/Add-StructuresLocateEvent.patch

@@ -241,7 +241,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @return {@link Location} where search begins
 +     */
 +    public @NotNull Location getOrigin() {
-+        return this.origin;
++        return this.origin.clone();
 +    }
 +
 +    /**

patches/api/Add-source-block-constructor-and-getChangedBlockData.patch

@@ -46,7 +46,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @NotNull
 +    public BlockData getChangedBlockData() {
-+        return changed;
++        return changed.clone();
 +    }
 +    // Paper end
 +

patches/api/Add-worldborder-events.patch

@@ -242,7 +242,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @NotNull
 +    public Location getOldCenter() {
-+        return this.oldCenter;
++        return this.oldCenter.clone();
 +    }
 +
 +    /**

patches/api/AsyncTabCompleteEvent.patch

@@ -208,7 +208,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @Nullable
 +    public Location getLocation() {
-+        return this.location;
++        return this.location != null ? this.location.clone() : null;
 +    }
 +
 +    /**
@@ -570,7 +570,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @org.jetbrains.annotations.Nullable
 +    public org.bukkit.Location getLocation() {
-+        return loc;
++        return this.loc != null ? this.loc.clone() : null;
 +    }
 +    // Paper end
 +

patches/api/BlockDestroyEvent.patch

@@ -79,9 +79,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    /**
 +     * @return The new state of this block (Air, or a Fluid type)
 +     */
-+    @NotNull
++    public @NotNull BlockData getNewState() {
-+    public BlockData getNewState() {
++        return this.newState.clone();
-+        return this.newState;
 +    }
 +
 +    /**

patches/api/Clone-mutables-to-prevent-unexpected-issues.patch

@@ -0,0 +1,151 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <jake.m.potrebic@gmail.com>
+Date: Sat, 16 Mar 2024 11:10:48 -0700
+Subject: [PATCH] Clone mutables to prevent unexpected issues
+
+There are lots of locations in the API where mutable
+types are not cloned, either on return or when passed
+as a parameter and assigned to a field, which can cause
+unexpected behaviors. Let this be a lesson to use
+immutable types for simple things Location, Vector, and
+others.
+
+diff --git a/src/main/java/org/bukkit/event/block/BlockCanBuildEvent.java b/src/main/java/org/bukkit/event/block/BlockCanBuildEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/block/BlockCanBuildEvent.java
++++ b/src/main/java/org/bukkit/event/block/BlockCanBuildEvent.java
+@@ -0,0 +0,0 @@ public class BlockCanBuildEvent extends BlockEvent {
+      */
+     @NotNull
+     public BlockData getBlockData() {
+-        return blockData;
++        return blockData.clone(); // Paper - clone because mutation isn't used
+     }
+ 
+     /**
+diff --git a/src/main/java/org/bukkit/event/entity/EntityChangeBlockEvent.java b/src/main/java/org/bukkit/event/entity/EntityChangeBlockEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/entity/EntityChangeBlockEvent.java
++++ b/src/main/java/org/bukkit/event/entity/EntityChangeBlockEvent.java
+@@ -0,0 +0,0 @@ public class EntityChangeBlockEvent extends EntityEvent implements Cancellable {
+      */
+     @NotNull
+     public BlockData getBlockData() {
+-        return to;
++        return to.clone(); // Paper - clone because mutation isn't used
+     }
+ 
+     @NotNull
+diff --git a/src/main/java/org/bukkit/event/entity/EntityExplodeEvent.java b/src/main/java/org/bukkit/event/entity/EntityExplodeEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/entity/EntityExplodeEvent.java
++++ b/src/main/java/org/bukkit/event/entity/EntityExplodeEvent.java
+@@ -0,0 +0,0 @@ public class EntityExplodeEvent extends EntityEvent implements Cancellable {
+      */
+     @NotNull
+     public Location getLocation() {
+-        return location;
++        return location.clone(); // Paper - clone to avoid changes
+     }
+ 
+     /**
+diff --git a/src/main/java/org/bukkit/event/entity/EntityPortalEnterEvent.java b/src/main/java/org/bukkit/event/entity/EntityPortalEnterEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/entity/EntityPortalEnterEvent.java
++++ b/src/main/java/org/bukkit/event/entity/EntityPortalEnterEvent.java
+@@ -0,0 +0,0 @@ public class EntityPortalEnterEvent extends EntityEvent {
+      */
+     @NotNull
+     public Location getLocation() {
+-        return location;
++        return location.clone(); // Paper - clone to avoid changes
+     }
+ 
+     @NotNull
+diff --git a/src/main/java/org/bukkit/event/entity/ItemDespawnEvent.java b/src/main/java/org/bukkit/event/entity/ItemDespawnEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/entity/ItemDespawnEvent.java
++++ b/src/main/java/org/bukkit/event/entity/ItemDespawnEvent.java
+@@ -0,0 +0,0 @@ public class ItemDespawnEvent extends EntityEvent implements Cancellable {
+      */
+     @NotNull
+     public Location getLocation() {
+-        return location;
++        return location.clone(); // Paper - clone to avoid changes
+     }
+ 
+     @NotNull
+diff --git a/src/main/java/org/bukkit/event/vehicle/VehicleBlockCollisionEvent.java b/src/main/java/org/bukkit/event/vehicle/VehicleBlockCollisionEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/vehicle/VehicleBlockCollisionEvent.java
++++ b/src/main/java/org/bukkit/event/vehicle/VehicleBlockCollisionEvent.java
+@@ -0,0 +0,0 @@ public class VehicleBlockCollisionEvent extends VehicleCollisionEvent {
+      */
+     @NotNull
+     public org.bukkit.util.Vector getVelocity() {
+-        return velocity;
++        return velocity.clone();
+     }
+     // Paper end
+ 
+diff --git a/src/main/java/org/bukkit/event/vehicle/VehicleMoveEvent.java b/src/main/java/org/bukkit/event/vehicle/VehicleMoveEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/vehicle/VehicleMoveEvent.java
++++ b/src/main/java/org/bukkit/event/vehicle/VehicleMoveEvent.java
+@@ -0,0 +0,0 @@ public class VehicleMoveEvent extends VehicleEvent {
+      */
+     @NotNull
+     public Location getFrom() {
+-        return from;
++        return from.clone(); // Paper - clone to avoid changes
+     }
+ 
+     /**
+@@ -0,0 +0,0 @@ public class VehicleMoveEvent extends VehicleEvent {
+      */
+     @NotNull
+     public Location getTo() {
+-        return to;
++        return to.clone(); // Paper - clone to avoid changes
+     }
+ 
+ 
+diff --git a/src/main/java/org/bukkit/event/world/GenericGameEvent.java b/src/main/java/org/bukkit/event/world/GenericGameEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/world/GenericGameEvent.java
++++ b/src/main/java/org/bukkit/event/world/GenericGameEvent.java
+@@ -0,0 +0,0 @@ public class GenericGameEvent extends WorldEvent implements Cancellable {
+      */
+     @NotNull
+     public Location getLocation() {
+-        return location;
++        return location.clone(); // Paper - clone to avoid changes
+     }
+ 
+     /**
+diff --git a/src/main/java/org/bukkit/event/world/SpawnChangeEvent.java b/src/main/java/org/bukkit/event/world/SpawnChangeEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/world/SpawnChangeEvent.java
++++ b/src/main/java/org/bukkit/event/world/SpawnChangeEvent.java
+@@ -0,0 +0,0 @@ public class SpawnChangeEvent extends WorldEvent {
+      */
+     @NotNull
+     public Location getPreviousLocation() {
+-        return previousLocation;
++        return previousLocation.clone(); // Paper - clone to avoid changes
+     }
+ 
+     @NotNull
+diff --git a/src/main/java/org/bukkit/event/world/StructureGrowEvent.java b/src/main/java/org/bukkit/event/world/StructureGrowEvent.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/event/world/StructureGrowEvent.java
++++ b/src/main/java/org/bukkit/event/world/StructureGrowEvent.java
+@@ -0,0 +0,0 @@ public class StructureGrowEvent extends WorldEvent implements Cancellable {
+      */
+     @NotNull
+     public Location getLocation() {
+-        return location;
++        return location.clone(); // Paper - clone to avoid changes
+     }
+ 
+     /**

patches/api/EntityPathfindEvent.patch

@@ -74,7 +74,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @NotNull
 +    public Location getLoc() {
-+        return this.location;
++        return this.location.clone();
 +    }
 +
 +    @Override

patches/api/PreCreatureSpawnEvent.patch

@@ -64,7 +64,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @NotNull
 +    public Location getSpawnLocation() {
-+        return this.location;
++        return this.location.clone();
 +    }
 +
 +    /**

patches/api/PreSpawnerSpawnEvent.patch

@@ -42,6 +42,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +    @NotNull
 +    public Location getSpawnerLocation() {
-+        return this.spawnerLocation;
++        return this.spawnerLocation.clone();
 +    }
 +}

patches/api/Turtle-API.patch

@@ -116,7 +116,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @NotNull
 +    public Location getLocation() {
-+        return this.location;
++        return this.location.clone();
 +    }
 +
 +    /**
@@ -210,7 +210,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     */
 +    @NotNull
 +    public Location getLocation() {
-+        return this.location;
++        return this.location.clone();
 +    }
 +
 +    @Override