如何在SliverList中显示滚动条？

SliverList(
  delegate: SliverChildBuilderDelegate(
    (BuildContext context, int index) {
      return ListTile(
        title: Text('Item $index'),
      );
    },
    childCount: 100,
  ),
)

Scrollbar(
  child: CustomScrollView(
    slivers: <Widget>[
      SliverList(
        delegate: SliverChildBuilderDelegate(
          (BuildContext context, int index) {
            return ListTile(
              title: Text('Item $index'),
            );
          },
          childCount: 100,
        ),
      ),
    ],
  ),
)