class A {
  late ;
  final int x;
  late ;
  final int? y;
}
class B extends A {
  int get x => 1;
  int? get y => 1;
}
class C extends A {
  late ;
  final int x = 2;
  late ;
  final int? y = 2;
}
main() {}
expect(expected, actual) {}
throws(f(), String message) {}