compile errors: mqtt libs have changed

[ThetaGamma]

The current mqtt_client_cpp v9.0.0-v4.0.0 will not work with the collector. Unfortunately I was not able to twist my mind around the errors to get a fix.

As a workaround, you need to use v3.1.0 to compile, which you get by downloading it from https://github.com/redboltz/mqtt_cpp/releases/tag/v3.1.0