Leashable API

paper-server/src/main/java/io/papermc/paper/entity/PaperLeashable.java

@@ -0,0 +1,50 @@
+package io.papermc.paper.entity;
+
+import com.google.common.base.Preconditions;
+import net.minecraft.world.entity.Leashable;
+import org.bukkit.craftbukkit.entity.CraftEntity;
+import org.bukkit.entity.Entity;
+
+public interface PaperLeashable extends io.papermc.paper.entity.Leashable {
+
+    Leashable getHandle();
+
+    @Override
+    default boolean isLeashed() {
+        return this.getHandle().getLeashHolder() != null;
+    }
+
+    @Override
+    default Entity getLeashHolder() throws IllegalStateException {
+        Preconditions.checkState(this.isLeashed(), "Entity not leashed");
+        return this.getHandle().getLeashHolder().getBukkitEntity();
+    }
+
+    private boolean unleash() {
+        if (!this.isLeashed()) {
+            return false;
+        }
+
+        this.getHandle().removeLeash();
+        return true;
+    }
+
+    @Override
+    default boolean setLeashHolder(Entity holder) {
+        if (this.getHandle() instanceof net.minecraft.world.entity.Entity entity && entity.generation) {
+            return false;
+        }
+
+        if (holder == null) {
+            return this.unleash();
+        }
+
+        if (holder.isDead()) {
+            return false;
+        }
+
+        this.unleash();
+        this.getHandle().setLeashedTo(((CraftEntity) holder).getHandle(), true);
+        return true;
+    }
+}

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftBoat.java

@@ -8,7 +8,7 @@ import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.entity.Boat;
 import org.bukkit.entity.Entity;
 
-public abstract class CraftBoat extends CraftVehicle implements Boat {
+public abstract class CraftBoat extends CraftVehicle implements Boat, io.papermc.paper.entity.PaperLeashable { // Paper - Leashable API
 
     public CraftBoat(CraftServer server, AbstractBoat entity) {
         super(server, entity);

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java

@@ -784,43 +784,17 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
 
     @Override
     public boolean isLeashed() {
-        if (!(this.getHandle() instanceof Mob)) {
+        return false; // Paper - implement in CraftMob & PaperLeashable
-            return false;
-        }
-        return ((Mob) this.getHandle()).getLeashHolder() != null;
     }
 
     @Override
     public Entity getLeashHolder() throws IllegalStateException {
-        Preconditions.checkState(this.isLeashed(), "Entity not leashed");
+        throw new IllegalStateException("Entity not leashed"); // Paper - implement in CraftMob & PaperLeashable
-        return ((Mob) this.getHandle()).getLeashHolder().getBukkitEntity();
-    }
-
-    private boolean unleash() {
-        if (!this.isLeashed()) {
-            return false;
-        }
-        ((Mob) this.getHandle()).removeLeash();
-        return true;
     }
 
     @Override
     public boolean setLeashHolder(Entity holder) {
-        if (this.getHandle().generation || (this.getHandle() instanceof WitherBoss) || !(this.getHandle() instanceof Mob)) {
+        return false; // Paper - implement in CraftMob & PaperLeashable
-            return false;
-        }
-
-        if (holder == null) {
-            return this.unleash();
-        }
-
-        if (holder.isDead()) {
-            return false;
-        }
-
-        this.unleash();
-        ((Mob) this.getHandle()).setLeashedTo(((CraftEntity) holder).getHandle(), true);
-        return true;
     }
 
     @Override

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java

@@ -11,7 +11,7 @@ import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Mob;
 import org.bukkit.loot.LootTable;
 
-public abstract class CraftMob extends CraftLivingEntity implements Mob {
+public abstract class CraftMob extends CraftLivingEntity implements Mob, io.papermc.paper.entity.PaperLeashable { // Paper - Leashable API
     public CraftMob(CraftServer server, net.minecraft.world.entity.Mob entity) {
         super(server, entity);
          paperPathfinder = new com.destroystokyo.paper.entity.PaperPathfinder(entity); // Paper - Mob Pathfinding API
@@ -175,4 +175,21 @@ public abstract class CraftMob extends CraftLivingEntity implements Mob {
         return getHandle().getExperienceReward((net.minecraft.server.level.ServerLevel) this.getHandle().level(), null);
     }
     // Paper end
+
+    // Paper start - Leashable API
+    @Override
+    public boolean isLeashed() {
+        return io.papermc.paper.entity.PaperLeashable.super.isLeashed();
+    }
+
+    @Override
+    public org.bukkit.entity.Entity getLeashHolder() throws IllegalStateException {
+        return io.papermc.paper.entity.PaperLeashable.super.getLeashHolder();
+    }
+
+    @Override
+    public boolean setLeashHolder(final org.bukkit.entity.Entity holder) {
+        return io.papermc.paper.entity.PaperLeashable.super.setLeashHolder(holder);
+    }
+    // Paper end - Leashable API
 }