在TabBarView中使用流（BLoC）时不会发出值

Question

我正在创建TabBarView，并且该视图的子级是使用BLoC模式创建的。当我在BLoC中使用基本流时，我的标签页中得到空结果。但是，当我将流切换为BehaviorSubject时，会收到预期的结果-带有列表的页面。为什么基本的Dart Streams无法同时工作？

（我正在使用Kiwi依赖注入-工作正常，没有提供的值为空）

BLoC类（Stream被BehaviorSubject替换）

class EventsListBloc implements BlocBase{

  Repository _repo;
  StreamSubscription _agendaSub;

  BehaviorSubject<List<Event>> _subject;

  StreamController<List<Event>> _eventController = StreamController<List<Event>>.broadcast();
  Sink<List<Event>> get _eventsInput => _eventController.sink;
  Stream<List<Event>> get eventsStream => _subject.stream;//_eventController.stream;

  EventsListBloc(){
    _repo = getContainer()<Repository>();
    _subject = BehaviorSubject();

    _agendaSub = _repo.eventsList.listen(_updateAgenda);
  }

  _updateAgenda(List<Event> eventsList){
    //_eventsInput.add(eventsList);
    _subject.value = eventsList;
  }

  void dispose() {
    print("EventsListBloc: disposing");
    _eventController.close();
    _agendaSub.cancel();
    _subject.close();
  }
}

TabBarView容器：

class AgendaPage extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    return _AgendaPageState();
  }
}

class _AgendaPageState extends State<AgendaPage>{

  Widget _provideListView(){
    return BlocProvider(
        bloc: EventsListBloc(),
        child: AgendaListWidget()
    );
  }

  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: 2,
      child: Scaffold(
          appBar: AppBar(
            title: Center(
                child: Text('Agenda')
            ),
            bottom: TabBar(
              tabs: <Widget>[
                Tab(
                  text: "test 1",
                ),
                Tab(
                  text: "test 2",
                )
              ],
            )//tabsy,
          ),
          body: TabBarView(
              children: [_provideListView(), _provideListView()]
          ),
      ),
    );
  }
}

标签页（正在使用BLoC的ListView）

class AgendaListWidget extends StatefulWidget{

  @override
  _AgendaListWidgetState createState() {
    return new _AgendaListWidgetState();
  }
}

class _AgendaListWidgetState extends State<AgendaListWidget> {

  Widget _buildItem(BuildContext context, Event event){
    var item = Card(
      child: Text(event.title),
    );

    return item;
  }

  Widget _buildList(BuildContext context){
    final eventsBloc = BlocProvider.of<EventsListBloc>(context);

    assert(eventsBloc != null);

    var result = StreamBuilder<List<Event>>(
      stream: eventsBloc.eventsStream,
      builder: (BuildContext context, AsyncSnapshot<List<Event>> snapshot) {
        if(snapshot.hasData){
          var result = ListView.builder(
            itemCount: snapshot.data.length,
            itemBuilder: (BuildContext context, int index) =>
              _buildItem(context, snapshot.data[index])
            ,
          );

          return result;
        }else{
          return const Text("Empty");
        }
      },
    );

    return result;
  }

  @override
  Widget build(BuildContext context) {
    return _buildList(context);
  }
}

BehaviorSubject的结果：

流的结果：