while (removeFrom.hasNext()) {
      if (!elementsToRetain.contains(removeFrom.next())) {
        removeFrom.remove();
        result = true;
      }
    }
    return result;
  }

  /**
   * Determines whether two iterators contain equal elements in the same order. More specifically,
   * this method returns {@code true} if {@code iterator1} and {@code iterator2} contain the same

        .testEquals();
  }

  private static class Container<T> {
    @SuppressWarnings("unused")
    public Container(T data) {}
  }

  public <T extends Container<String>> void testConstructor_parameterTypes()
      throws NoSuchMethodException {
    @SuppressWarnings("rawtypes") // Reflection API skew
    Constructor<Container> constructor = Container.class.getConstructor(Object.class);

        .inOrder();
  }

  public void testCartesianProduct_contains() {
    Set<List<Integer>> actual = Sets.cartesianProduct(set(1, 2), set(3, 4));
    assertTrue(actual.contains(list(1, 3)));
    assertTrue(actual.contains(list(1, 4)));
    assertTrue(actual.contains(list(2, 3)));
    assertTrue(actual.contains(list(2, 4)));
    assertFalse(actual.contains(list(3, 1)));
  }

  public void testCartesianProduct_equals() {

  }

  public void test_contains_nonnull_yes() {
    Iterator<@Nullable String> set = Arrays.<@Nullable String>asList("a", null, "b").iterator();
    assertTrue(Iterators.contains(set, "b"));
  }

  public void test_contains_nonnull_no() {
    Iterator<String> set = asList("a", "b").iterator();
    assertFalse(Iterators.contains(set, "c"));
  }

  public void test_contains_null_yes() {

   * keys and values are the result of applying the provided mapping functions to the input
   * elements. The generated map is sorted by the specified comparator.
   *
   * <p>If the mapped keys contain duplicates (according to the specified comparator), an {@code
   * IllegalArgumentException} is thrown when the collection operation is performed. (This differs

      }

      @Override
      public boolean contains(@CheckForNull Object element) {
        return set1.contains(element) && !set2.contains(element);
      }
    };
  }

  /**
   * Returns an unmodifiable <b>view</b> of the symmetric difference of two sets. The returned set
   * contains all elements that are contained in either {@code set1} or {@code set2} but not in

        .testEquals();
  }

  private static class Container<T> {
    @SuppressWarnings("unused")
    public Container(T data) {}
  }

  public <T extends Container<String>> void testConstructor_parameterTypes()
      throws NoSuchMethodException {
    @SuppressWarnings("rawtypes") // Reflection API skew
    Constructor<Container> constructor = Container.class.getConstructor(Object.class);

    @Override
    public void clear() {
      synchronized (mutex) {
        delegate().clear();
      }
    }

    @Override
    public boolean contains(@CheckForNull Object o) {
      synchronized (mutex) {
        return delegate().contains(o);
      }
    }

    @Override
    public boolean containsAll(Collection<?> c) {
      synchronized (mutex) {
        return delegate().containsAll(c);

   * keys and values are the result of applying the provided mapping functions to the input
   * elements. The generated map is sorted by the specified comparator.
   *
   * <p>If the mapped keys contain duplicates (according to the specified comparator), an {@code
   * IllegalArgumentException} is thrown when the collection operation is performed. (This differs

        .containsExactly(Maps.immutableEntry(4, "d"), Maps.immutableEntry(2, "b"))
        .inOrder();
    assertThat(diff1.entriesOnlyOnRight().entrySet()).contains(Maps.immutableEntry(6, "z"));
    assertThat(diff1.entriesInCommon().entrySet()).contains(Maps.immutableEntry(1, "a"));
    assertThat(diff1.entriesDiffering().entrySet())
        .containsExactly(
            Maps.immutableEntry(5, ValueDifferenceImpl.create("e", "g")),