Context
I need to get the current speed of the aircraft.
Efforts
Looking at the documentation, I can see that exists the method WaypointMissionOperator.getAutoFlightSpeed which gives me that info.
Problem
While implementing the code, this method was missing. Was it moved, renamed or something?
Environment
Have a look at the FlightControllerState class, it contains the current status of pretty much all of the aircraft components.
Specifically, you should look at FlightController.setStateCallback(). This returns current information, specifically you want to use getVelocityX, getVelocityY and getVelocityZ.
There are also keys for each, the documentation gives the details.
Having X, Y and Z velocities, the speed can be computed in this way:
final speed = sqrt(pow(velocity.x, 2) + pow(velocity.y, 2) + pow(velocity.z, 2));