Nesting SliverList inside StreamBuilder

import 'package:flutter/material.dart';
import 'package:rxdart/rxdart.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MainPage(),
    );
  }
}

class MainPage extends StatelessWidget {
  final iBloc = IntBloc();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Put something'),
      ),
      body: CustomScrollView(
        slivers: <Widget>[
          StreamBuilder<int>(
            stream: iBloc.currentInt,
            builder: (ctx, snapshot) {
              // This one works
              // return SliverToBoxAdapter(
              //   child: Text('trying using sliver'),
              // );

              switch (snapshot.connectionState) {
                case ConnectionState.active:
                  // Neither of these works

                  // return Text('active');
                  return SliverToBoxAdapter(
                    child: Text('active'),
                  );
                  break;
                case ConnectionState.done:
                  return Text('done');
                  break;
                case ConnectionState.waiting:
                  return Text('waiting');
                  break;
                default:
                  return Text('something');
              }
            },
          )
        ],
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          iBloc.addOne();
        },
        child: Icon(Icons.add),
      ),
    );
  }
}

class IntBloc {
  int n = 0;

  final _intBloc = BehaviorSubject<int>();

  Observable<int> get currentInt => _intBloc.stream;

  IntBloc() {
    _intBloc.add(n);
  }

  void addOne() {
    n += 1;
    _intBloc.add(n);
  }
}