code: public static int hash(long input)
      {
          int low = (int) input;
          int high = (int) (input >>> 32);
  
          int k1 = mixK1(low);
          int h1 = mixH1(DEFAULT_SEED, k1);
  
          k1 = mixK1(high);
          h1 = mixH1(h1, k1);
  
          return fmix(h1, SizeOf.SIZE_OF_LONG);
      }
docs: Special-purpose version for hashing a single long value. Value is treated as little-endian