It is probably socket activated (that is how it works in Ubuntu at least), so there is nothing defined in that unit, as there is no need for it to be defined.
And by the way, I highly suggest not using forking unit type and instead spawn services in the foreground 
Yep, my current file uses foreground but I originally used forking because of some issues around the beam and foreground daemon’s at the time. Regardless I think PidFile is mostly antiquated anymore anyway, distillary/releases I think have the functionality built in now?