*
 * @author Hayward Chan
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
class ForwardingImmutableCollection {
  private ForwardingImmutableCollection() {}

 * delegation to save code size.
 *
 * @author Hayward Chan
 */
// TODO: Make this class GWT serializable.
@ElementTypesAreNonnullByDefault
class ForwardingImmutableCollection<E> extends ImmutableCollection<E> {

  final transient Collection<E> delegate;

  ForwardingImmutableCollection(Collection<E> delegate) {
    this.delegate = delegate;
  }

  @Override
  public UnmodifiableIterator<E> iterator() {