}
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two arrays of unsigned {@code long} values <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(long, long)}), the first pair of values that follow any common
   * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For

    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code boolean} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(boolean, boolean)}), the first pair of values that follow any
   * common prefix, or when one array is a prefix of the other, treats the shorter array as the

    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code boolean} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(boolean, boolean)}), the first pair of values that follow any
   * common prefix, or when one array is a prefix of the other, treats the shorter array as the

    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code char} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>; not advisable
   * for sorting user-visible strings as the ordering may not match the conventions of the user's
   * locale. That is, it compares, using {@link #compare(char, char)}), the first pair of values

    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code short} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(short, short)}), the first pair of values that follow any
   * common prefix, or when one array is a prefix of the other, treats the shorter array as the

    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code short} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(short, short)}), the first pair of values that follow any
   * common prefix, or when one array is a prefix of the other, treats the shorter array as the

    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code long} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(long, long)}), the first pair of values that follow any common
   * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For

    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code int} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(int, int)}), the first pair of values that follow any common
   * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For

               *
               * The next combination is
               *
               * {0, 1, ..., bitToFlip - firstSetBit - 2, bitToFlip, ...}
               *
               * This is lexicographically next if you look at the combinations in descending order
               * e.g. {2, 1, 0}, {3, 1, 0}, {3, 2, 0}, {3, 2, 1}, {4, 1, 0}...
               */

              bits.set(0, bitToFlip - firstSetBit - 1);

   *
   * <p><i>Notes:</i> This is an implementation of the algorithm for Lexicographical Permutations
   * Generation, described in Knuth's "The Art of Computer Programming", Volume 4, Chapter 7,
   * Section 7.2.1.2. The iteration order follows the lexicographical order. This means that the
   * first permutation will be in ascending order, and the last will be in descending order.
   *