Iterators.addAll(list, iterator());
      return list;
    }
  }

  /** @serialData the ConcurrentMap of elements and their counts. */
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(countMap);
  }

  @J2ktIncompatible // serialization
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {

      Iterators.addAll(list, iterator());
      return list;
    }
  }

  /** @serialData the ConcurrentMap of elements and their counts. */
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(countMap);
  }

  @J2ktIncompatible // serialization
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {