}

  private static long shiftMix(long val) {
    return val ^ (val >>> 47);
  }

  /** Implementation of Hash128to64 from util/hash/hash128to64.h */
  @VisibleForTesting
  static long hash128to64(long high, long low) {
    long a = (low ^ high) * K3;
    a ^= (a >>> 47);
    long b = (high ^ a) * K3;
    b ^= (b >>> 47);
    b *= K3;
    return b;
  }

  /**