* 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 // java.io.ObjectOutputStream
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(keyTypeOrObjectUnderJ2cl);
    Serialization.writeMap(this, stream);
  }

  @SuppressWarnings("unchecked") // reading field populated by writeObject
  @GwtIncompatible // java.io.ObjectInputStream

    }

    @Override
    protected void doWriteTo(final StreamOutput out) throws IOException {
        out.writeOptionalString(modelName);
        out.writeOptionalString(featureSetName);
        out.writeMap(params);
        out.writeOptionalStringArray(activeFeatures != null ? activeFeatures.toArray(new String[0]) : null);
        out.writeOptionalString(storeName);
    }

    @Override

    stream.defaultWriteObject();
    stream.writeObject(keyTypeOrObjectUnderJ2cl);
    stream.writeObject(valueTypeOrObjectUnderJ2cl);
    Serialization.writeMap(this, stream);
  }

  @SuppressWarnings("unchecked") // reading fields populated by writeObject
  @GwtIncompatible // java.io.ObjectInputStream