Google Calendar API -创建/插入/添加事件- C# -错误403

using Google.Apis.Auth.OAuth2;
using Google.Apis.Calendar.v3;
using Google.Apis.Calendar.v3.Data;
using Google.Apis.Services;

// 创建事件
public Event CreateEvent(string calendarId, string summary, DateTime startTime, DateTime endTime)
{
    var credential = GoogleCredential.FromFile("credentials.json")
        .CreateScoped(CalendarService.Scope.Calendar);

    var service = new CalendarService(new BaseClientService.Initializer
    {
        HttpClientInitializer = credential
    });

    var newEvent = new Event
    {
        Summary = summary,
        Start = new EventDateTime { DateTime = startTime },
        End = new EventDateTime { DateTime = endTime }
    };

    return service.Events.Insert(newEvent, calendarId).Execute();
}

// 插入事件
public Event InsertEvent(string calendarId, string eventId, string summary, DateTime startTime, DateTime endTime)
{
    var credential = GoogleCredential.FromFile("credentials.json")
        .CreateScoped(CalendarService.Scope.Calendar);

    var service = new CalendarService(new BaseClientService.Initializer
    {
        HttpClientInitializer = credential
    });

    var newEvent = new Event
    {
        Id = eventId,
        Summary = summary,
        Start = new EventDateTime { DateTime = startTime },
        End = new EventDateTime { DateTime = endTime }
    };

    return service.Events.Insert(newEvent, calendarId).Execute();
}

// 添加事件
public Event AddEvent(string calendarId, string eventId)
{
    var credential = GoogleCredential.FromFile("credentials.json")
        .CreateScoped(CalendarService.Scope.Calendar);

    var service = new CalendarService(new BaseClientService.Initializer
    {
        HttpClientInitializer = credential
    });

    return service.Events.Get(calendarId, eventId).Execute();
}