N1QL DML is not preserving expiration set by the SDK

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using Couchbase.Core;

using Couchbase.Configuration;

using Couchbase;

using Couchbase.Configuration.Client;

using System.Configuration;

namespace ConsoleApplication4

{

    class Program

    {

        static void Main(string[] args)

        {

            var config = new ClientConfiguration

            {

                Servers = new List<Uri> { new Uri("http://10.0.0.44:8091/pools") },

                UseSsl = false,

                DefaultOperationLifespan = 1000,

                BucketConfigs = new Dictionary<string, BucketConfiguration>

                {

                  {"default", new BucketConfiguration

                  {

                      BucketName = "default",

                      UseSsl = false,

                      Password = "",

                      DefaultOperationLifespan = 2000,

                      PoolConfiguration = new PoolConfiguration

                      {

                        MaxSize = 10,

                        MinSize = 5,

                        SendTimeout = 12000

                      }

                  }

                 }

                }

            };

            Cluster cbCluster = new Cluster(config);

            Document<object> cbDoc = new Document<dynamic> { Id = "01", Content = new { a="a", b=1}, Expiry=5*60*1000 };

            using (var cbBucket = cbCluster.OpenBucket())

            {

                var upd = cbBucket.Upsert(cbDoc);

                if (upd.Success)

                {

                    Console.WriteLine("before N1ql update - Expiry:" + cbDoc.Expiry.ToString());

                    Console.ReadKey();

                }

                var get = cbBucket.GetDocument<dynamic>("01");

                if (get.Success)

                {

                    Console.WriteLine("after N1ql update - Expiry:" + get.Document.Expiry.ToString());

                    Console.ReadKey();

                }

            }

        }

    }

}