Add API to retrieve an attribute modifier from a UUID (#9924)

* Add attribute modifier from UUID API

* Add method to remove by UUID

* Add overload for UnmodifiableAttributeInstance, better precondition messages

* rebase

2 files changed, 90 insertions, 0 deletions

diff --git a/patches/api/0447-Add-UUID-attribute-modifier-API.patch b/patches/api/0447-Add-UUID-attribute-modifier-API.patch
new file mode 100644
index 0000000000..251ae6e425
--- /dev/null
+++ b/patches/api/0447-Add-UUID-attribute-modifier-API.patch
@@ -0,0 +1,34 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: TonytheMacaroni <[email protected]>
+Date: Thu, 9 Nov 2023 20:35:35 -0500
+Subject: [PATCH] Add UUID attribute modifier API
+
+
+diff --git a/src/main/java/org/bukkit/attribute/AttributeInstance.java b/src/main/java/org/bukkit/attribute/AttributeInstance.java
+index 5513174ea545bb5b4fdc028cbaa4c1bb763e2c6d..3cffffe8106387847b10ac39f96687bb075ef686 100644
+--- a/src/main/java/org/bukkit/attribute/AttributeInstance.java
++++ b/src/main/java/org/bukkit/attribute/AttributeInstance.java
+@@ -39,6 +39,23 @@ public interface AttributeInstance {
+     @NotNull
+     Collection<AttributeModifier> getModifiers();
+ 
++    // Paper start
++    /**
++     * Gets the modifier with the corresponding UUID.
++     *
++     * @param uuid the UUID of the modifier
++     * @return the modifier, if it exists
++     */
++    @org.jetbrains.annotations.Nullable AttributeModifier getModifier(@NotNull java.util.UUID uuid);
++
++    /**
++     * Remove a modifier with the corresponding UUID from this instance.
++     *
++     * @param uuid the UUID of the modifier
++     */
++    void removeModifier(@NotNull java.util.UUID uuid);
++    // Paper end
++
+     /**
+      * Add a modifier to this instance.
+      *
diff --git a/patches/server/1051-Add-UUID-attribute-modifier-API.patch b/patches/server/1051-Add-UUID-attribute-modifier-API.patch
new file mode 100644
index 0000000000..62d8cf7c98
--- /dev/null
+++ b/patches/server/1051-Add-UUID-attribute-modifier-API.patch
@@ -0,0 +1,56 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: TonytheMacaroni <[email protected]>
+Date: Thu, 9 Nov 2023 20:34:44 -0500
+Subject: [PATCH] Add UUID attribute modifier API
+
+
+diff --git a/src/main/java/io/papermc/paper/attribute/UnmodifiableAttributeInstance.java b/src/main/java/io/papermc/paper/attribute/UnmodifiableAttributeInstance.java
+index 52439f4b959c74027eb191a3af960c70beb978e8..a2c057d92ea34368c7efc538b6e5b15ef342c54e 100644
+--- a/src/main/java/io/papermc/paper/attribute/UnmodifiableAttributeInstance.java
++++ b/src/main/java/io/papermc/paper/attribute/UnmodifiableAttributeInstance.java
+@@ -5,6 +5,7 @@ import org.bukkit.attribute.Attribute;
+ import org.bukkit.attribute.AttributeModifier;
+ import org.bukkit.craftbukkit.attribute.CraftAttributeInstance;
+ 
++import java.util.UUID;
+ import java.util.Collection;
+ 
+ public class UnmodifiableAttributeInstance extends CraftAttributeInstance {
+@@ -18,6 +19,11 @@ public class UnmodifiableAttributeInstance extends CraftAttributeInstance {
+         throw new UnsupportedOperationException("Cannot modify default attributes");
+     }
+ 
++    @Override
++    public void removeModifier(UUID uuid) {
++        throw new UnsupportedOperationException("Cannot modify default attributes");
++    }
++
+     @Override
+     public void addModifier(AttributeModifier modifier) {
+         throw new UnsupportedOperationException("Cannot modify default attributes");
+diff --git a/src/main/java/org/bukkit/craftbukkit/attribute/CraftAttributeInstance.java b/src/main/java/org/bukkit/craftbukkit/attribute/CraftAttributeInstance.java
+index 0029412b1242879deb898524001bb4cc7550fa78..8e8b0a09ef58a4a3ccc31f2e11a0d6b9f3ee9b39 100644
+--- a/src/main/java/org/bukkit/craftbukkit/attribute/CraftAttributeInstance.java
++++ b/src/main/java/org/bukkit/craftbukkit/attribute/CraftAttributeInstance.java
+@@ -44,6 +44,21 @@ public class CraftAttributeInstance implements AttributeInstance {
+         return result;
+     }
+ 
++    // Paper start
++    @Override
++    public AttributeModifier getModifier(java.util.UUID uuid) {
++        Preconditions.checkArgument(uuid != null, "UUID cannot be null");
++        net.minecraft.world.entity.ai.attributes.AttributeModifier modifier = this.handle.getModifier(uuid);
++        return modifier == null ? null : CraftAttributeInstance.convert(modifier);
++    }
++
++    @Override
++    public void removeModifier(java.util.UUID uuid) {
++        Preconditions.checkArgument(uuid != null, "UUID cannot be null");
++        this.handle.removeModifier(uuid);
++    }
++    // Paper end
++
+     @Override
+     public void addModifier(AttributeModifier modifier) {
+         Preconditions.checkArgument(modifier != null, "modifier");