/**
 * GWT emulated version of {@link ImmutableList}. TODO(cpovirk): more doc
 *
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
abstract class ForwardingImmutableList<E> extends ImmutableList<E> {

  ForwardingImmutableList() {}

  abstract List<E> delegateList();

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

import java.util.List;

/**
 * GWT emulated version of {@link SingletonImmutableList}.
 *
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
final class SingletonImmutableList<E> extends ForwardingImmutableList<E> {

  final transient List<E> delegate;
  // This reference is used both by the custom field serializer, and by the
  // GWT compiler to infer the elements of the lists that needs to be
  // serialized.