boolean containsZero = chars.get(0);
    // Compute the hash table.
    char[] table = new char[chooseTableSize(size)];
    int mask = table.length - 1;
    for (int c = chars.nextSetBit(0); c != -1; c = chars.nextSetBit(c + 1)) {
      // Compute the filter at the same time.
      filter |= 1L << c;
      int index = smear(c) & mask;
      while (true) {
        // Check for empty.
        if (table[index] == 0) {

    }
    return result;
  }

  private static String allMatchingChars(BitSet bitSet) {
    char[] result = new char[bitSet.cardinality()];
    for (int j = 0, c = bitSet.nextSetBit(0); j < result.length; ++j) {
      result[j] = (char) c;
      c = bitSet.nextSetBit(c + 1);
    }
    return new String(result);
  }

  private static String newTestString(Random random, BitSet bitSet, int percentMatching) {