How to add complex data type to custom class?

If I want to recreate a simple class like this in flutterflow:

class FmRecordData {
  final String layoutName;
  final Map<String, dynamic> fieldValueMap;

  FmRecordData({
    required this.layoutName,
    required this.fieldValueMap,
  });
}

how would I do that with flutterflow? in the data type dropdown there is no option for maps.