}

  /**
   * @serialData the key class, value class, number of entries, first key, first value, second key,
   *     second value, and so on.
   */
  @GwtIncompatible // java.io.ObjectOutputStream
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(keyTypeOrObjectUnderJ2cl);
    stream.writeObject(valueTypeOrObjectUnderJ2cl);

  }

  /**
   * @serialData the key class, value class, number of entries, first key, first value, second key,
   *     second value, and so on.
   */
  @GwtIncompatible // java.io.ObjectOutputStream
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(keyTypeOrObjectUnderJ2cl);
    stream.writeObject(valueTypeOrObjectUnderJ2cl);