问如何在flutter中使用google日历api获取一个月内的所有活动？

EN

date_utils: ^0.1.0+3

googleapis_auth: ^0.2.11+1

googleapis: ^0.54.0

final GoogleSignIn _googleSignIn =
        GoogleSignIn(
          scopes: <String>[
            CalendarApi.CalendarScope,
          ],
        )

signInWithGoogle() async {
   await _googleSignIn.signIn();
   final headers = await _googleSignIn.currentUser.authHeaders;
   getEvent(headers);
}


getEvent(headers) async {
final httpClient = GoogleHttpClient(headers);
var calendar = CalendarApi(httpClient);
DateTime lastMonth = Utils.lastDayOfMonth(DateTime.now());
DateTime firstMonth = Utils.firstDayOfMonth(DateTime.now());
var calEvents = calendar.events.list("primary", timeMax: lastMonth.toUtc(), timeMin: firstMonth.toUtc());
calEvents.then(
    (events) => {events.items.forEach((event) => print("EVENT ${event.summary}"))});
}

 import 'package:http/io_client.dart';
import 'package:http/http.dart';

class GoogleHttpClient extends IOClient {
Map<String, String> _headers;

 GoogleHttpClient(this._headers) : super();

 @override
 Future<StreamedResponse> send(BaseRequest request) =>
  super.send(request..headers.addAll(_headers));

 @override
 Future<Response> head(Object url, {Map<String, String> headers}) =>
  super.head(url, headers: headers..addAll(_headers));

 }