Flutter get data from firebase and show on ui using Stream Builder

Flutter get data from firebase and show on ui using Stream Builder:

class LabelRepository{

Stream<List<Labels>> listOfLabels() {
  return reference      .snapshots()
      .map((event) => event.documents)
      .map((event) => event.map((e) => Labels.fromMap(e.data)).toList());

}//////////////////////////////////////////////////////////////////////////////////////

Expanded(

  child: StreamBuilder(
    stream: LabelRepository().listOfLabels(),    builder: (BuildContext context, snapshot) {
      if (!snapshot.hasData) {
        return CircularProgressIndicator();      }
      return Scrollbar(
        child: ListView.builder(
            shrinkWrap: true,            scrollDirection: Axis.vertical,            itemCount: snapshot.data.length,            itemBuilder: (BuildContext context, int index) {
              var color = 0xFFF+snapshot.data[index].color;              return Row(
                children: <Widget>[
                  Padding(
                    padding: const EdgeInsets.all(8.0),                    child: Container(
                      padding: EdgeInsets.all(18.0),                      height: 40,                      decoration: BoxDecoration(
                          shape: BoxShape.circle,                          color: Colors.green),                      child: Text(" "),                    ),                  ),                  Expanded(
                    child: ListTile(
                      title: Text(
                        snapshot.data[index].title,                        style: TextStyle(
                            color: Colors.black, fontSize: 14),                      ),                      onTap: () {
                        Navigator.pop(context);                      },