How to merge the Google APIs Client library with the Gdata client library to access Google Contacts using C#

Google Contacts V3 for c#

using Google.Apis.Auth.OAuth2;
using Google.Apis.Util.Store;
using Google.GData.Client;
using Google.GData.Contacts;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace GoogleContactsTest
{
    class Program
    {
        static void Main(string[] args)
        {
            // Install-Package Google.GData.Contacts
            // Install-Package Google.Apis.Auth

            var clientId = "XXX.apps.googleusercontent.com";
            var clientSecret = "XXX";

            string[] scopes = new string[] { "https://www.google.com/m8/feeds/" };           

            // Requesting Authentication or loading previously stored authentication for userName
            UserCredential credential = GoogleWebAuthorizationBroker.AuthorizeAsync(new ClientSecrets { ClientId = clientId, ClientSecret = clientSecret }
                                                                                         , scopes
                                                                                         , "xya"
                                                                                         , CancellationToken.None
                                                                                         , new FileDataStore("Google Contacts V3")).Result;

            var m = credential.GetAccessTokenForRequestAsync();
            var requestFactory = new GDataRequestFactory(null);
            requestFactory.CustomHeaders.Add("Authorization: Bearer " + credential.Token.AccessToken);
            var service = new ContactsService("App Name") { RequestFactory = requestFactory };
            FeedQuery feed = new FeedQuery();
            string feedUrl = "https://www.google.com/m8/feeds/contacts/default/full";

            // Instantiate a SpreadsheetQuery object to retrieve spreadsheets.
            ContactsQuery myQuery = new ContactsQuery(feedUrl);
            ContactsFeed resultFeed = service.Query(myQuery);
            foreach (var contact in resultFeed.Entries) {
                var l = contact.Title;            
            }
        }
    }
}