Custom Functions Struct Scheme can't copy Object using fromSerializableMap

I created two custom structs : "Question" and "Reponse".

"Question" is defined like that :

{
  List<ReponseStruct> values,
  String? title
}

And at some time I need to add a row to the values list of a QuestionStruct object.
So I wrote a custom function to do this :

QuestionStruct addAnswerRow(QuestionStruct currentQuestion) {
  QuestionStruct copy = QuestionStruct.fromSerializableMap( currentQuestion.toSerializableMap() );
  List<ReponseStruct> temp = List<ReponseStruct>.from( copy.values );
  temp.add(new ReponseStruct());
  copy.values = temp;
  return copy;
}

I tried this function using Android Studio directly, and there is no error when compiling it / using it.

So I tried to write this on FlutterFlow :

And I have this error :

The method 'fromSerializableMap' isn't defined for the type 'QuestionStruct'. Try correcting the name to the name of an existing method, or defining a method named 'fromSerializableMap'.

Does anybody know why I have this error ?
I checked the source code, and the function is actually here :

For those looking for a solution, just replace :

QuestionStruct copy = QuestionStruct.fromSerializableMap( currentQuestion.toSerializableMap() );

By :

QuestionStruct copy = QuestionStruct.fromMap( currentQuestion.toMap() );