The stless and friends macros should generate code that uses the new super param feature if it is available. Super parameters are available when the lower SDK bound of the package is at least 2.17.0-0.

The stless macro should for example generate the following code:

class Foo extends StatelessWidget {
  const Foo({super.key});

  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

More about super parameters: dart-lang/language#1855
Tracking issue for the flutter framework: flutter/flutter#100575
Same request for Dart Code: Dart-Code/Dart-Code#3899