// ImmutableCollection.iterator() appear consistent to javac's type inference.
  @Override
  public abstract UnmodifiableIterator<E> iterator();

  abstract static class CachingAsList<E> extends ImmutableSet<E> {
    @LazyInit private transient ImmutableList<E> asList;

    @Override
    public ImmutableList<E> asList() {
      ImmutableList<E> result = asList;
      if (result == null) {

  }

  // This declaration is needed to make Set.iterator() and
  // ImmutableCollection.iterator() consistent.
  @Override
  public abstract UnmodifiableIterator<E> iterator();

  abstract static class CachingAsList<E> extends ImmutableSet<E> {
    @LazyInit @RetainedWith private transient @Nullable ImmutableList<E> asList;

    @Override
    public ImmutableList<E> asList() {
      ImmutableList<E> result = asList;