Classes not being generated with class-modifiers about built_value.dart HOT 3 CLOSED

I succeeded by using the @dart directive as shown below.
I don't know if this is the right way.
Is there any other way?

// @dart = 2.18
import 'package:built_value/built_value.dart';

part 'api_service_response.g.dart';

@BuiltValue(instantiable: false)
abstract class APIServiceResponse extends Object with APIServiceResponseValues {
  APIServiceResponse rebuild(void Function(APIServiceResponseBuilder) updates);
  APIServiceResponseBuilder toBuilder();
}
... ...
...

from built_value.dart.

I tried again after removing the pubspec.lock file and it worked.
There seems to have been an issue with dart 3.0 in pubspec dependencies.

from built_value.dart.

Interesting! Not sure how that happened. If you (or anyone else reading this) figure out a way to repro, please let me know. Thanks.

from built_value.dart.