private void OnDirectoryChangedMessageReceive(DirectoryChangedMessage obj)
 {
     Assert.IsNotNull(obj);
     _messageDelivered = true;
 }
        private async void OnDirectoryChangedMessageReceive(DirectoryChangedMessage obj)
        {
            _logger.Info("received message of type 'DirectoryChangedMessage'. --> Clean(null)");
            _logger.Info("delay clean: " + obj.DelayClean);

            if (obj.DelayClean)
            {
                _logger.Info("delay for 20 sec.");
                await Task.Delay(20000);
            }

            _logger.Info("execute Clean(null)");
            Clean(null);
        }