ForwardingImmutableList() {}

  abstract List<E> delegateList();

  @Override
  public int indexOf(@Nullable Object object) {
    return delegateList().indexOf(object);
  }

  @Override
  public int lastIndexOf(@Nullable Object object) {
    return delegateList().lastIndexOf(object);
  }

  @Override
  public E get(int index) {
    return delegateList().get(index);
  }

  @Override

  private final ImmutableCollection<E> delegate;
  private final ImmutableList<? extends E> delegateList;

  RegularImmutableAsList(ImmutableCollection<E> delegate, ImmutableList<? extends E> delegateList) {
    this.delegate = delegate;
    this.delegateList = delegateList;
  }

  RegularImmutableAsList(ImmutableCollection<E> delegate, Object[] array) {

  private final Set<?> delegate;
  private final ImmutableList<E> delegateList;

  JdkBackedImmutableSet(Set<?> delegate, ImmutableList<E> delegateList) {
    this.delegate = delegate;
    this.delegateList = delegateList;
  }

  @Override
  E get(int index) {
    return delegateList.get(index);
  }

  @Override
  public boolean contains(@Nullable Object object) {

  RegularImmutableList(List<E> delegate) {
    // TODO(cpovirk): avoid redundant unmodifiableList wrapping
    this.delegate = unmodifiableList(delegate);
  }

  @Override
  List<E> delegateList() {
    return delegate;
  }

  private final E element;

  SingletonImmutableList(E element) {
    this.delegate = singletonList(checkNotNull(element));
    this.element = element;
  }

  @Override
  List<E> delegateList() {
    return delegate;
  }