WitherSkeleton witherSkeleton = player.getWorld().spawn(player.getLocation(), WitherSkeleton.class);

            PacketContainer packet = new PacketContainer(PacketType.Play.Server.ENTITY_METADATA);
            packet.getIntegers().write(0, witherSkeleton.getEntityId());

            WrappedDataWatcher watcher = WrappedDataWatcher.getEntityWatcher(witherSkeleton).deepClone();

            WrappedDataWatcher.Serializer serializer = WrappedDataWatcher.Registry.get(Boolean.class);
            watcher.setObject(new WrappedDataWatcher.WrappedDataWatcherObject(3, serializer), true);
            packet.getWatchableCollectionModifier().write(0, watcher.getWatchableObjects());

            ProtocolLibrary.getProtocolManager().sendServerPacket(player, packet);