Paper/nms-patches/BiomeTheEndDecorator.patch

--- a/net/minecraft/server/BiomeTheEndDecorator.java
+++ b/net/minecraft/server/BiomeTheEndDecorator.java
@@ -21,7 +21,7 @@
             EntityEnderDragon entityenderdragon = new EntityEnderDragon(this.a);
 
             entityenderdragon.setPositionRotation(0.0D, 128.0D, 0.0D, this.b.nextFloat() * 360.0F, 0.0F);
-            this.a.addEntity(entityenderdragon);
+            this.a.addEntity(entityenderdragon, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.CHUNK_GEN); // CraftBukkit - add SpawnReason
         }
 
     }