public ResponseAsyncContext(ClientHttpRequestCompletedEventArgs completedEventArgs)
            {
                this.cancelled = completedEventArgs.Cancelled;
                this.error     = completedEventArgs.Error;
                if (this.error == null)
                {
                    this.response = completedEventArgs.Response;
                }
                this.userState = completedEventArgs.UserState;

                this.completedEventArgs = completedEventArgs;
            }
            public ResponseAsyncContext(ClientHttpRequestCompletedEventArgs completedEventArgs)
            {
                this.cancelled = completedEventArgs.Cancelled;
                this.error = completedEventArgs.Error;
                this.response = completedEventArgs.Response;
                this.userState = completedEventArgs.UserState;

                this.completedEventArgs = completedEventArgs;
            }