super(forwardList);
    }
  }

  /** An implementation of {@link List#hashCode()}. */
  static int hashCodeImpl(List<?> list) {
    // TODO(lowasser): worth optimizing for RandomAccess?
    int hashCode = 1;
    for (Object o : list) {
      hashCode = 31 * hashCode + (o == null ? 0 : o.hashCode());

      hashCode = ~~hashCode;