I would like to add a few fields to the stats mqtt topic. I am using a modified version of the UDP packet forwarder. The fields are such as battery voltage, relative-humidity, and temperature. Does the gateway bridge format this content in the CustomData field automatically to the mqtt stats topic or do I have to tweak someplace in the loraserver code.
You have to implement this yourself in the source-code 
Thanks for the reply @brocaar , much appreciated. Any pointers in the right direction would be appreciated as I noticed that the stats message definitions for the were in loraserver/app/gw. Is this where to start off for this? I tried looking through the gateway bridge but I found no references to the stats message.