mqtt publish in callback example not working with Mosquitto 3.1 about pubsubclient

[knolleary]

Hi - thanks for this. I put this example together in a hurry and didn't spot this problem. There is an obvious mistake; the code should take a copy of the payload before passing it back to publish otherwise the payload is partially overwritten as the PUBLISH packet is constructed. I'll push a fix when I have time to test it properly later.

Ironically, I've just started putting together a unit test framework for this library to ensure the library and all of the examples work as expected. Currently it just verifies they compile cleanly - functional verification was the job for one night this week.

[knolleary]

I've just commited a fix: 5ffa607

The fix worked for me.

Thanks Nicholas.