private void CreateCompletedEventArgs(Task<HttpResponseMessage> task)
 {
     completedEventArgs = new PostSenderCompletedEventArgs();
     completedEventArgs.Success = task.IsGeneralSuccess() && task.Result.IsSuccessStatusCode;
     completedEventArgs.Result = completedEventArgs.Success
         ? task.Result.Content.ReadAsStringAsync().Result : null;
 }