ImmutableSortedSet<String> set =
        ImmutableSortedSet.copyOf(new String[] {"e", "a", "e", "f", "b", "i", "d", "a", "c", "k"});
    assertThat(set.ceiling("l")).isNull();
  }

  public void testSubSetExclusiveExclusive() {
    String[] strings = NUMBER_NAMES.toArray(new String[0]);
    ImmutableSortedSet<String> set = ImmutableSortedSet.copyOf(strings);
    Arrays.sort(strings);
    for (int i = 0; i < strings.length; i++) {