问Azure AD Graph API组搜索

EN

public List<myModel> SearchGroups(string term)
    {
        List<myModel> returnList = new List<myModel>();

       //my service root uri
        Uri serviceRoot = new Uri(serviceRootURL);

        //create the client and get authorization
        ActiveDirectoryClient adClient = new ActiveDirectoryClient(serviceRoot, async () => await GetAppTokenAsync());

        //get collection of IGroup
        IPagedCollection<IGroup> groups = adClient.Groups.ExecuteAsync().Result;

        //do while loop because groups are returned in paged list...
        do
        {
            List<IGroup> directoryObjects = groups.CurrentPage.ToList();

            //get groups that contain the search term
            foreach (IGroup item in directoryObjects.Where(x=>x.DisplayName.ToLower().Contains(term.ToLower())))
            {
                returnList.Add(new myModel(item as Microsoft.Azure.ActiveDirectory.GraphClient.Group));          
            }
            //get next page of results
            groups = groups.GetNextPageAsync().Result;

        } while (groups.MorePagesAvailable); //also tried while(groups != null) same issue

        return returnList;
    }

groups = groups.GetNextPageAsync().Result;