Converter<Object, dynamic> fuse(Converter<String, dynamic> other)

Fuses this with other.

Encoding with the resulting converter is equivalent to converting with this before converting with other.

Source 

Converter<Object, dynamic> fuse(Converter<String, dynamic> other) {
  if (other is Utf8Encoder) {
    return new JsonUtf8Encoder(indent, _toEncodable);
  }
  return super.fuse(other);
}