The origin of HIGH_LATENCY2.airspeed_sp

HIGH_LATENCY and HIGH_LATENCY2 MAVLink messages include only the most important attributes about the vehicle. Both the deprecated HIGH_LATENCY and the new HIGH_LATENCY2 messages include airspeed_sp attribute (Airspead setpoint). Apparently it’s an important one, but I cannot find Airspead setpoint attribute in any other common MAVLink messages.

SPL satellite telemetry fills HIGH_LATENCY(2) report using multiple other MAVLink messages reported by the autopilot. So far airspeed_sp is not populated because I cannot find a source MAVLink message to retrieve/compute the value from.

Also where the airspead setpoint is shown in QGC and Mission Planner?