Is there a way to replace the mirror package for flutter?

this is flutter rsocket-dart code.

https://github.com/rsocket/rsocket-dart/blob/master/lib/route/reflection.dart

but, I cant't to use this library in flutter, because this package use 'dart:mirrors' packages.
So, I want to change this code.

but, I very very low level... I can't to understood this code...

import 'dart:mirrors';

import '../rsocket.dart';
import 'package:collection/collection.dart' show IterableExtension;

RSocketService? getRSocketServiceAnnotation(dynamic instance) {
  final DeclarationMirror clazzDeclaration = reflectClass(instance.runtimeType);
  final classMirror = reflectClass(RSocketService);
  final annotationInstanceMirror =
      clazzDeclaration.metadata.firstWhereOrNull((d) => d.type == classMirror);
  if (annotationInstanceMirror == null) {
    print('Annotation is not on this class');
    return null;
  }
  return annotationInstanceMirror.reflectee as RSocketService?;
}

How can I change this code to not use mirror?