protected override async Task SubscribeAsync(string correlationId)
        {
            // Check if already were subscribed
            if (_subscribed)
            {
                return;
            }

            // Subscribe to the topic
            var topic = GetTopic();
            var qos   = (MqttQualityOfServiceLevel)_qos;
            await _connection.SubscribeAsync(topic, qos, this);

            _subscribed = true;
        }