}

  public void testContains_no() {
    assertFalse("contains(notPresent) should return false", collection.contains(e3()));
  }

  @CollectionFeature.Require(ALLOWS_NULL_QUERIES)
  public void testContains_nullNotContainedButQueriesSupported() {
    assertFalse("contains(null) should return false", collection.contains(null));
  }

  @CollectionFeature.Require(absent = ALLOWS_NULL_QUERIES)