return forwardList.contains(object);
    }

    @Override
    public int indexOf(@CheckForNull Object object) {
      int index = forwardList.lastIndexOf(object);
      return (index >= 0) ? reverseIndex(index) : -1;
    }

    @Override
    public int lastIndexOf(@CheckForNull Object object) {
      int index = forwardList.indexOf(object);
      return (index >= 0) ? reverseIndex(index) : -1;
    }

      return forwardList.contains(object);
    }

    @Override
    public int indexOf(@CheckForNull Object object) {
      int index = forwardList.lastIndexOf(object);
      return (index >= 0) ? reverseIndex(index) : -1;
    }

    @Override
    public int lastIndexOf(@CheckForNull Object object) {
      int index = forwardList.indexOf(object);
      return (index >= 0) ? reverseIndex(index) : -1;
    }

  }

  @Override
  public int indexOf(@Nullable Object object) {
    return (object == null) ? -1 : Lists.indexOfImpl(this, object);
  }

  @Override
  public int lastIndexOf(@Nullable Object object) {
    return (object == null) ? -1 : Lists.lastIndexOfImpl(this, object);
  }

  public final boolean addAll(int index, Collection<? extends E> newElements) {