No spawning mobs

ChunkProviderServerHook.java

/**
 * @author PaulBGD
 */
public class ChunkProviderServerHook extends ChunkProviderServer {

    @Setter
    private static int distance = FactionConfiguration.getConfiguration().spawnProtection;

    public ChunkProviderServerHook(WorldServer worldserver, IChunkLoader ichunkloader, IChunkProvider ichunkprovider) {
        super(worldserver, ichunkloader, ichunkprovider);
    }

    @Override
    public List<BiomeBase.BiomeMeta> getMobsFor(EnumCreatureType enumcreaturetype, BlockPosition blockposition) {
        SerializedLocation serializedLocation = FactionConfiguration.getConfiguration().spawn;
        if (MathUtils.square(serializedLocation.x - blockposition.getX()) + MathUtils.square(serializedLocation.z - blockposition.getZ()) < MathUtils.square(distance)) {
            return ImmutableList.of(); // empty list, as no mobs spawn here
        }
        return super.getMobsFor(enumcreaturetype, blockposition);
    }

    public static void setup(org.bukkit.World world) {
        WorldServer handle = ((CraftWorld) world).getHandle();
        ChunkProviderServer chunkProviderServer = handle.chunkProviderServer;
        IChunkLoader iChunkLoader = null;
        try {
            Field chunkLoader = ChunkProviderServer.class.getDeclaredField("chunkLoader");
            chunkLoader.setAccessible(true);
            iChunkLoader = (IChunkLoader) chunkLoader.get(chunkProviderServer);
        } catch (NoSuchFieldException | IllegalAccessException e) {
            e.printStackTrace();
        }
        ChunkProviderServerHook hook = new ChunkProviderServerHook(handle, iChunkLoader, chunkProviderServer.chunkProvider);
        // transfer fields
        hook.unloadQueue = chunkProviderServer.unloadQueue;
        hook.chunks = chunkProviderServer.chunks;
    }

}