}
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code byte} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(byte, byte)}), 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

    ImmutableList<String> b = ImmutableList.of("b");

    testComparator(lexy, empty, a, aa, ab, b);

    new EqualsTester()
        .addEqualityGroup(lexy, Comparators.lexicographical(comparator))
        .addEqualityGroup(Comparators.lexicographical(String.CASE_INSENSITIVE_ORDER))
        .addEqualityGroup(Ordering.natural())
        .testEquals();
  }

  public void testIsInOrder() {