StreamGroup close never completes unless removed first

[curt-weber]

StreamGroup close documentation states that it will close when streams in the group close, but this doesn't appear to be the case:

import 'dart:async';
import 'package:async/async.dart';

Future<void> main() async {
  final controller = StreamController.broadcast();
  final group = StreamGroup.broadcast();
  group.add(controller.stream);
  await controller.close();
  print('controller closed');
  await group.close();
  print('never');
}

The above will close properly if the controllers stream is removed before calling close. Am I missing something?