* for the data format.
   */
  static <K extends @Nullable Object, V extends @Nullable Object> void populateMap(
      Map<K, V> map, ObjectInputStream stream, int size)
      throws IOException, ClassNotFoundException {
    for (int i = 0; i < size; i++) {
      @SuppressWarnings("unchecked") // reading data stored by writeMap
      K key = (K) stream.readObject();

   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    Serialization.writeMap(this, stream);
  }

  @GwtIncompatible
  @J2ktIncompatible
    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();