通过多因素身份验证获取Sharepoint ClientContext后如何获取ProjectContext？

Question

对于要启用MFA的客户端，我想通过CSOM / C＃与Project Onine进行交互。在下面的代码段中，我可以通过我认为的共享点MFA（调试器经过这些行），但是如何获得Project Online的上下文呢？强制转换失败（并且我认为我从错误消息中了解了原因），那么我该怎么办？

private static bool GetMultiFactorAuthCookie(string pwaPath)
{
    bool error = false;
    var authManager = new AuthenticationManager();
    ClientContext sharepointClientContext = authManager.GetWebLoginClientContext(pwaPath);

    web = sharepointClientContext.Web;
    user = web.CurrentUser;

    sharepointClientContext.Load(web);
    sharepointClientContext.Load(user);
    sharepointClientContext.ExecuteQuery();

    ProjectContext projContext = sharepointClientContext.CastTo<ProjectContext>(sharepointClientContext);

    return !error;
}

调试器告诉我

  

无法从“ Microsoft.SharePoint.Client.ClientContext”转换为“ Microsoft.SharePoint.Client.ClientObject”