Method isSpawnChunk

src/main/java/net/minecraft/world/World.java:3858–3865

Returns true if the chunk is located near the spawn point

(int x, int z)

     * Returns true if the chunk is located near the spawn point
     */
    public boolean isSpawnChunk(int x, int z)
    {
        BlockPos blockpos = this.getSpawnPoint();
        int i = x * 16 + 8 - blockpos.getX();
        int j = z * 16 + 8 - blockpos.getZ();
        int k = 128;
        return i >= -k && i <= k && j >= -k && j <= k;
    }
}