Why do brick:Heating_Valve and brick:Cooling_Valve not extend brick:Valve?

[bresaur]

brick:Heating_Valve and brick:Cooling_Valve extend brick:HVACEquipment, not brick:Valve.

There may be a reason for this, but I did not get it from reading the documentation.
After all, there is HVAC_Valve which extends both brick:HVACEquipment and brick:Valve, so why is brick:Heating_Valve not a subClassOf HVAC:Valve?

Looking at changes in generate_brick.py, it looks like this can be traced back to from #333:
previously, define_classes was called for valve_subclasses with parent=BRICK.Valve
afterwards, define_classes(hvac_valve_subclasses, BRICK.HVAC_Equipment) and
define_classes(valve_subclasses, BRICK.Equipment)