title: Publish multiple topics in one message MQTT
body: <p>I have a device that collects a large amount of data from different sensors and I want to send them to my broker in a single message. On the client side, I just want to see some of that data at a given time, I do not want to see them all. Can I publish several topics in a message and then on the client side see only some of these topics? I know that I can subscribe to several topics with the wildcard # but I do not know how to send several topics in a single message. One solution is to send each topic separately in different messages, but I have a lot of sensors and it would be very slow.</p>