@CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = {ZERO, ONE})
  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);
  }

  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_otherSetWithDifferentElements() {
    Collection<E> elements = getSampleElements(getNumElements() - 1);
    elements.add(getSubjectGenerator().samples().e3());

    assertFalse(
        "A Set should not equal another Set containing different elements.",
        getSet().equals(MinimalSet.from(elements)));
  }

  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_otherSetWithDifferentElements() {
    Collection<E> elements = getSampleElements(getNumElements() - 1);
    elements.add(getSubjectGenerator().samples().e3());

    assertFalse(
        "A Set should not equal another Set containing different elements.",
        getSet().equals(MinimalSet.from(elements)));
  }

    }
  }

  protected E[] createSamplesArray() {
    E[] array = getSubjectGenerator().createArray(getNumElements());
    getSampleElements().toArray(array);
    return array;
  }

  protected E[] createOrderedArray() {
    E[] array = getSubjectGenerator().createArray(getNumElements());
    getOrderedElements().toArray(array);
    return array;
  }

  @Override
  public void setUp() throws Exception {
    super.setUp();
    navigableSet = (NavigableSet<E>) getSet();
    values =
        copyToList(
            getSubjectGenerator()
                .getSampleElements(getSubjectGenerator().getCollectionSize().getNumElements()));
    sort(values, navigableSet.comparator());

    // some tests assume SEVERAL == 3
    if (values.size() >= 1) {
      a = values.get(0);

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNull_supported() {
    E[] array = createArrayWithNullElement();
    collection = getSubjectGenerator().create(array);
    expectContents(array);
  }

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

              ?, ? extends OneSizeTestContainerGenerator<SetMultimap<K, V>, Entry<K, V>>>
          parentBuilder) {
    return SetTestSuiteBuilder.using(
            new MultimapGetGenerator<K, V>(parentBuilder.getSubjectGenerator()))
        .withFeatures(computeMultimapGetFeatures(parentBuilder.getFeatures()))
        .named(parentBuilder.getName() + ".get[key]")
        .suppressing(parentBuilder.getSuppressedTests())
        .createTestSuite();

              ?, ? extends OneSizeTestContainerGenerator<ListMultimap<K, V>, Entry<K, V>>>
          parentBuilder) {
    return ListTestSuiteBuilder.using(
            new MultimapGetGenerator<K, V>(parentBuilder.getSubjectGenerator()))
        .withFeatures(computeMultimapGetFeatures(parentBuilder.getFeatures()))
        .named(parentBuilder.getName() + ".get[key]")
        .suppressing(parentBuilder.getSuppressedTests())
        .createTestSuite();

  @CollectionSize.Require(SEVERAL)
  public void testOrderingAffectsEqualsComparisons() {
    ListMultimap<K, V> multimap1 =
        getSubjectGenerator()
            .create(mapEntry(k0(), v0()), mapEntry(k0(), v1()), mapEntry(k0(), v0()));
    ListMultimap<K, V> multimap2 =
        getSubjectGenerator()
            .create(mapEntry(k0(), v1()), mapEntry(k0(), v0()), mapEntry(k0(), v0()));

    assertFalse(getMultiset().addAll(Collections.emptySet()));
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_emptyMultiset() {
    assertFalse(getMultiset().addAll(getSubjectGenerator().create()));
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_nonEmptyList() {
    assertTrue(getMultiset().addAll(asList(e3(), e4(), e3())));