}

  public void test_contains_nonnull_iterable_yes() {
    Iterable<@Nullable String> set = iterable("a", null, "b");
    assertTrue(Iterables.contains(set, "b"));
  }

  public void test_contains_nonnull_iterable_no() {
    Iterable<String> set = iterable("a", "b");
    assertFalse(Iterables.contains(set, "c"));
  }

  public void testGetOnlyElement_noDefault_valid() {