Using Named parameters inside Custom Actions

I see in dart we can use named parameters to call a function :

I try to replicate this in flutterflow.

This usual code is working but don't accepts named parameters :

Future<void> myTest(
  String message,
  int durationSec,
) async {
// The code
}
myTest("hello", 2);

But this code with braces tells me "Failed to process parameters" :

Future<void> myTest({
  String message,
  int durationSec,}
) async {
// The code
}

myTest(message:"hello", durationSec: 2);

Why ? Is there a special way to do it with flutterflow ?

Thank you