Null after future

main.dart

class Test {
  final String text;
  
  Test({
    required this.text,
  });

  Future<void> hello() async {
    await Future.delayed(Duration(seconds: 2));
    print(text);
  }
}

void main() {
  Test? test = Test(text: 'Hello!!!');
  
  print('Start');
  test.hello();
  test = null;
  print('End');
}