}

        // Perform a partition with the selected median.
        int low = from + 1, high = to; // Indexes for partitioning.
        double partition = array[from + 1]; // Choose partitioning element.
        while (true) {
          // Skip the elements smaller than the partition.
          do {
            low++;
          } while (array[low] < partition);

          // Skip the elements larger than the partition.

        }

        // Perform a partition with the selected median.
        int low = from + 1, high = to; // Indexes for partitioning.
        double partition = array[from + 1]; // Choose partitioning element.
        while (true) {
          // Skip the elements smaller than the partition.
          do {
            low++;
          } while (array[low] < partition);

          // Skip the elements larger than the partition.

        hashFunction.newHasher().putUnencodedChars(string).hash());
  }

  static char randomLowSurrogate(Random random) {
    return (char)
        (Character.MIN_LOW_SURROGATE
            + random.nextInt(Character.MAX_LOW_SURROGATE - Character.MIN_LOW_SURROGATE + 1));
  }

  static char randomHighSurrogate(Random random) {
    return (char)
        (Character.MIN_HIGH_SURROGATE

    char[] surrogates = {
      MAX_LOW_SURROGATE, MAX_HIGH_SURROGATE, MIN_LOW_SURROGATE, MIN_HIGH_SURROGATE,
    };
    for (char surrogate : surrogates) {
      builder.add(newString(surrogate));
      builder.add(newString(surrogate, 'n'));
      builder.add(newString('n', surrogate));
      builder.add(newString(surrogate, surrogate));
    }
    builder.add(newString(MIN_LOW_SURROGATE, MAX_HIGH_SURROGATE));

    String[] BAD_STRINGS = {
      String.valueOf(Character.MIN_LOW_SURROGATE),
      Character.MIN_LOW_SURROGATE + "xyz",
      "abc" + Character.MIN_LOW_SURROGATE,
      "abc" + Character.MIN_LOW_SURROGATE + "xyz",
      String.valueOf(Character.MAX_LOW_SURROGATE),
      Character.MAX_LOW_SURROGATE + "xyz",
      "abc" + Character.MAX_LOW_SURROGATE,
      "abc" + Character.MAX_LOW_SURROGATE + "xyz",
    };
    for (String s : BAD_STRINGS) {

    char[] surrogates = {
      MAX_LOW_SURROGATE, MAX_HIGH_SURROGATE, MIN_LOW_SURROGATE, MIN_HIGH_SURROGATE,
    };
    for (char surrogate : surrogates) {
      builder.add(newString(surrogate));
      builder.add(newString(surrogate, 'n'));
      builder.add(newString('n', surrogate));
      builder.add(newString(surrogate, surrogate));
    }
    builder.add(newString(MIN_LOW_SURROGATE, MAX_HIGH_SURROGATE));

   *         <li><b>If the next character was a valid low surrogate, the code point value of the
   *             high/low surrogate pair is returned.</b>
   *         <li>If the next character was not a low surrogate value, then {@link
   *             IllegalArgumentException} is thrown.
   *       </ol>
   *   <li>If the first character was a low surrogate value, {@link IllegalArgumentException} is
   *       thrown.

    int k1 = mixK1(input);
    int h1 = mixH1(seed, k1);

    return fmix(h1, Ints.BYTES);
  }

  @Override
  public HashCode hashLong(long input) {
    int low = (int) input;
    int high = (int) (input >>> 32);

    int k1 = mixK1(low);
    int h1 = mixH1(seed, k1);

    k1 = mixK1(high);
    h1 = mixH1(h1, k1);

    return fmix(h1, Longs.BYTES);
  }

  @Override

    // Two differing invalid pairs.
    assertEquals("\uDCABdef", Strings.commonSuffix("abc\uDCAB\uDCABdef", "abc\uDCAC\uDCABdef"));
    // One orphan low surrogate.
    assertEquals("", Strings.commonSuffix("x\uD8AB\uDCAB", "\uDCAB"));
    // Two orphan low surrogates.
    assertEquals("\uDCAB", Strings.commonSuffix("\uDCAB", "\uDCAB"));
  }

  public void testValidSurrogatePairAt() {

    // center will be at either low or high.
    int low = requiredFrom;
    int high = requiredTo;
    while (high > low + 1) {
      int mid = (low + high) >>> 1;
      if (allRequired[mid] > centerFloor) {
        high = mid;
      } else if (allRequired[mid] < centerFloor) {
        low = mid;
      } else {