unfiltered.add("zzz");
                unfiltered.add("abc");
                return Collections2.filter(Collections2.filter(unfiltered, LENGTH_1), NOT_YYY_ZZZ);
              }
            })
        .named("Collections2.filter, filtered input")
        .withFeatures(
            CollectionFeature.SUPPORTS_ADD,
            CollectionFeature.SUPPORTS_REMOVE,

  @Override
  NavigableSet<Integer> createUnfiltered(Iterable<Integer> contents) {
    return Sets.newTreeSet(contents);
  }

  @Override
  NavigableSet<Integer> filter(
      NavigableSet<Integer> elements, Predicate<? super Integer> predicate) {
    return Sets.filter(elements, predicate);
  }

  @Override
  Iterable<Integer> createUnfiltered(Iterable<Integer> contents) {
    return Lists.newArrayList(contents);
  }

  @Override
  Iterable<Integer> filter(Iterable<Integer> elements, Predicate<? super Integer> predicate) {
    return Iterables.filter(elements, predicate);
  }

    assertThat(stream(FluentIterable.of(1, 2, 3)).filter(n -> n > 1)).containsExactly(2, 3);
  }

  @SuppressWarnings("deprecation")
  public void testStream_collection() {
    assertThat(stream(Arrays.asList())).isEmpty();
    assertThat(stream(Arrays.asList("a"))).containsExactly("a");
    assertThat(stream(Arrays.asList(1, 2, 3)).filter(n -> n > 1)).containsExactly(2, 3);
  }

   */
  // TODO(kevinb): how can we omit that Iterables link when building gwt
  // javadoc?
  public static <E extends @Nullable Object> Collection<E> filter(
      Collection<E> unfiltered, Predicate<? super E> predicate) {
    if (unfiltered instanceof FilteredCollection) {
      // Support clear(), removeAll(), and retainAll() when filtering a filtered
      // collection.

   * java.util.stream.Stream#filter}. This method is not being deprecated, but we gently encourage
   * you to migrate to streams.
   */
  // TODO(kevinb): how to omit that last sentence when building GWT javadoc?
  public static <E extends @Nullable Object> Set<E> filter(
      Set<E> unfiltered, Predicate<? super E> predicate) {
    if (unfiltered instanceof SortedSet) {
      return filter((SortedSet<E>) unfiltered, predicate);

    Method method;
    try {
      method = extractMethod(test);
    } catch (IllegalArgumentException e) {
      logger.finer(Platform.format("%s: including by default: %s", test, e.getMessage()));
      return true;
    }
    if (suppressedTests.contains(method)) {
      logger.finer(Platform.format("%s: excluding because it was explicitly suppressed.", test));
      return false;
    }
    TesterRequirements requirements;

  static <E extends @Nullable Object> Collection<E> filterCollection(
      Collection<E> collection, Predicate<? super E> predicate) {
    if (collection instanceof Set) {
      return Sets.filter((Set<E>) collection, predicate);
    } else {
      return Collections2.filter(collection, predicate);
    }
  }

  @Override
  public boolean containsKey(@CheckForNull Object key) {
    return asMap().get(key) != null;
  }

  @Override

  private static class HasBoth extends TypeA implements TypeB {}

  @GwtIncompatible // Iterables.filter(Iterable, Class)
  public void testFilterByType_iterator() throws Exception {
    HasBoth hasBoth = new HasBoth();
    Iterable<TypeA> alist = Lists.newArrayList(new TypeA(), new TypeA(), hasBoth, new TypeA());
    Iterable<TypeB> blist = Iterables.filter(alist, TypeB.class);
    assertThat(blist).containsExactly(hasBoth).inOrder();
  }

      // Can't check isDefault() for JDK 7 compatibility.
      if (!Modifier.isAbstract(method.getModifiers())) {
        continue;
      }
      // The interface could be package-private or private.
      // filter out equals/hashCode/toString
      if (method.getName().equals("equals")
          && method.getParameterTypes().length == 1
          && method.getParameterTypes()[0] == Object.class) {
        continue;
      }