assertFalse("addAll(n, nothing) should return false", getList().addAll(0, emptyCollection()));
    expectUnchanged();
  }

  @ListFeature.Require(absent = SUPPORTS_ADD_WITH_INDEX)
  public void testAddAllAtIndex_unsupportedNothing() {
    try {
      assertFalse(
          "addAll(n, nothing) should return false or throw",
          getList().addAll(0, emptyCollection()));

  public void testAddAll_supportedNothing() {
    assertFalse("addAll(nothing) should return false", collection.addAll(emptyCollection()));
    expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  public void testAddAll_unsupportedNothing() {
    try {
      assertFalse(
          "addAll(nothing) should return false or throw", collection.addAll(emptyCollection()));

    assertFalse("addAll(n, nothing) should return false", getList().addAll(0, emptyCollection()));
    expectUnchanged();
  }

  @ListFeature.Require(absent = SUPPORTS_ADD_WITH_INDEX)
  public void testAddAllAtIndex_unsupportedNothing() {
    try {
      assertFalse(
          "addAll(n, nothing) should return false or throw",
          getList().addAll(0, emptyCollection()));

  public void testAddAll_supportedNothing() {
    assertFalse("addAll(nothing) should return false", collection.addAll(emptyCollection()));
    expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  public void testAddAll_unsupportedNothing() {
    try {
      assertFalse(
          "addAll(nothing) should return false or throw", collection.addAll(emptyCollection()));

              @Override
              public SortedSet<String> create(String[] elements) {
                SortedSet<String> set = new TreeSet<>(arbitraryNullFriendlyComparator());
                Collections.addAll(set, elements);
                return set;
              }
            })
        .named("TreeSet, with comparator")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,

  private static final ImmutableSet<String> PS_NOT_RS =
      ImmutableSet.of("blogspot.com", "blogspot.co.uk", "uk.com");

  private static final ImmutableSet<String> PS =
      ImmutableSet.<String>builder().addAll(RS).addAll(PS_NOT_RS).build();

  private static final ImmutableSet<String> NO_PS =
      ImmutableSet.of("www", "foo.ihopethiswillneverbeapublicsuffix", "x.y.z");

  /**

    assertTrue(
        "add(somePresent) should return true", getSet().addAll(MinimalCollection.of(e3(), e0())));
    expectAdded(e3());
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_withDuplicates() {
    MinimalCollection<E> elementsToAdd = MinimalCollection.of(e3(), e4(), e3(), e4());
    assertTrue("add(hasDuplicates) should return true", getSet().addAll(elementsToAdd));
    expectAdded(e3(), e4());
  }

              @Override
              public Collection<String> create(String[] elements) {
                List<String> unfiltered = newArrayList();
                unfiltered.add("yyy");
                Collections.addAll(unfiltered, elements);
                unfiltered.add("zzz");
                return Collections2.filter(unfiltered, NOT_YYY_ZZZ);
              }
            })
        .named("Collections2.filter")

              @Override
              public Collection<String> create(String[] elements) {
                List<String> unfiltered = newArrayList();
                unfiltered.add("yyy");
                Collections.addAll(unfiltered, elements);
                unfiltered.add("zzz");
                return Collections2.filter(unfiltered, NOT_YYY_ZZZ);
              }
            })
        .named("Collections2.filter")

        set.addAll(set1);
        set.addAll(set2);
        return set;
      }

      @Override
      @SuppressWarnings({"nullness", "unchecked"}) // see supertype
      public ImmutableSet<@NonNull E> immutableCopy() {
        ImmutableSet.Builder<@NonNull E> builder =
            new ImmutableSet.Builder<@NonNull E>()
                .addAll((Iterable<@NonNull E>) set1)