nonEmptyProperSubset = new Target(MinimalCollection.of(e1()), "subset");
    sameElements = new Target(asList(createSamplesArray()), "sameElements");
    containsDuplicates =
        new Target(MinimalCollection.of(e0(), e0(), e3(), e3()), "containsDuplicates");
    partialOverlap = new Target(MinimalCollection.of(e2(), e3()), "partialOverlap");
    nullSingleton = new Target(Collections.<E>singleton(null), "nullSingleton");
  }

    nonEmptyProperSubset = new Target(MinimalCollection.of(e1()), "subset");
    sameElements = new Target(asList(createSamplesArray()), "sameElements");
    containsDuplicates =
        new Target(MinimalCollection.of(e0(), e0(), e3(), e3()), "containsDuplicates");
    partialOverlap = new Target(MinimalCollection.of(e2(), e3()), "partialOverlap");
    nullSingleton = new Target(Collections.<E>singleton(null), "nullSingleton");
  }

  public void testRetainAll_duplicatesKept() {
    E[] array = createSamplesArray();
    array[1] = e0();
    collection = getSubjectGenerator().create(array);
    assertFalse(
        "containsDuplicates.retainAll(superset) should return false",
        collection.retainAll(MinimalCollection.of(createSamplesArray())));
    expectContents(array);
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)