MQTT consumer sets its subscribeTopicName as a exchange property, and it will be used by MQTT producer as a destination if it exists in the route.
If you have a following route:
MQTT consumer put "topicIn" to "MQTTTopicPropertyName" exchange property, and MQTT producer uses this property to determine a destination topic to publish. Then MQTT producer ignores publishTopicName and send a message to "topicIn", so MQTT consumer consumes the message again, eventually it causes infinite delivery. We need to stop this property to be used as a destination for producer.