DocumentDBRepository.GetItemsAsync C# (CSharp) Метод

        public static async Task<IEnumerable<T>> GetItemsAsync(Expression<Func<T, bool>> predicate)
        {
            IDocumentQuery<T> query = client.CreateDocumentQuery<T>(
                UriFactory.CreateDocumentCollectionUri(DatabaseId, CollectionId),
                new FeedOptions { MaxItemCount = -1 })
                .Where(predicate)
                .AsDocumentQuery();
            List<T> results = new List<T>();
            while (query.HasMoreResults)
            {
                results.AddRange(await query.ExecuteNextAsync<T>());
            }
            return results;
        }
        public static async Task<Document> CreateItemAsync(T item)

        private async Task AddtoDatabase(Activity message, string TeamorConversationId, string mebId)
        {
            var user = new UserDetails();

            //var TeamorConversationId = channelData.Team != null ? channelData.Team.Id : message.Conversation.Id;
            user.EmaildId = await GetUserEmailId(mebId, message.ServiceUrl, TeamorConversationId);

            user.UserId   = mebId;
            user.UserName = await GetUserName(mebId, message.ServiceUrl, TeamorConversationId);

            if (user.UserName != null)
            {
                user.UserName = user.UserName.Split(' ').FirstOrDefault();
            }
            user.Type = Helper.Constants.NewUser;
            var existinguserRecord = await DocumentDBRepository.GetItemsAsync <UserDetails>(u => u.EmaildId == user.EmaildId && u.Type == Helper.Constants.NewUser);

            if (existinguserRecord.Count() == 0)
            {
                var NewUserRecord = await DocumentDBRepository.CreateItemAsync(user);
            }
        }