I am already familiar with this topic. Everyone else only uses gtfs:stop_id:<country>-<operator> and gtfs:stop_name:<country>-<operator>(*). You use 
gtfs:stop_id:<country>-<operator>,
gtfs:shape_id:<country>-<operator>,
gtfs:route_id:<country>-<operator> (duplicate to ref).

That's why I suspected that this was a detail of the source that should be noted under the key source. You seem to have confirmed this for me.

(*) The stop may have a different name locally, especially if several operators use the stop.