Citing Leukbaars 

Hotspotting is a technique to quickly assign uv's to UV islands by referencing a predefined uv atlas.

I've created this material for the game I'm making, sharing it while I hope someone finds it useful. You can use it together with Leukbaars' Blender addon, Dream UV. 

It uses the ORM format for Occlusion Roughness and Metalness. So the ORM contains the Occlusion map in the red channel, the Rouhgness map in the green channel and the Metalness in the Blue channel.