assertFalse("contains(null) should return false", collection.contains(null));
  }

  @CollectionFeature.Require(absent = ALLOWS_NULL_QUERIES)
  public void testContains_nullNotContainedAndUnsupported() {
    expectNullMissingWhenNullUnsupported("contains(null) should return false or throw");
  }

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nonNullWhenNullContained() {

  @CollectionFeature.Require(absent = ALLOWS_NULL_VALUES)
  public void testAddAtIndex_nullUnsupported() {
    assertThrows(NullPointerException.class, () -> getList().add(0, null));
    expectUnchanged();
    expectNullMissingWhenNullUnsupported("Should not contain null after unsupported add(n, null)");
  }

  @ListFeature.Require(SUPPORTS_ADD_WITH_INDEX)
  public void testAddAtIndex_negative() {