Paper/paper-server/nms-patches/net/minecraft/world/item/ItemMonsterEgg.patch

--- a/net/minecraft/world/item/ItemMonsterEgg.java
+++ b/net/minecraft/world/item/ItemMonsterEgg.java
@@ -177,10 +177,10 @@
                     return Optional.empty();
                 } else {
                     ((EntityInsentient) object).moveTo(vec3d.x(), vec3d.y(), vec3d.z(), 0.0F, 0.0F);
-                    worldserver.addFreshEntityWithPassengers((Entity) object);
+                    worldserver.addFreshEntityWithPassengers((Entity) object, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.SPAWNER_EGG); // CraftBukkit
                     ((EntityInsentient) object).setCustomName((IChatBaseComponent) itemstack.get(DataComponents.CUSTOM_NAME));
                     itemstack.consume(1, entityhuman);
-                    return Optional.of(object);
+                    return Optional.of((EntityInsentient) object); // CraftBukkit - decompile error
                 }
             }
         }