expectContents(createArrayWithNullElement());
  }

  @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testRetainAll_nullSingletonPreviouslySeveralWithNull() {
    initCollectionWithNullElement();
    expectReturnsTrue(nullSingleton);
    expectContents(nullSingleton.toRetain);
  }

  // nullSingleton.retainAll()