When adding an ImpulseManeuver with a PositionAngleDetector as trigger to a propagator, a NullPointerException is raised.

Answered by @bryan

The problem is that the PositionAngleDetector is not initialized. Therefore, the offsetEstimators parameter of the PositionAngleDetector is not initialized too. That’s why you have a NullPointerException. I wonder if the init() method of the ImpulseManeuverDetector should call the init() method of the trigger parameter to make sure it is initialized. Something like:

/** {@inheritDoc} */
public void init(final SpacecraftState s0, final AbsoluteDate t) {
    trigger.init(s0, t);
    forward = t.durationFrom(s0.getDate()) >= 0;
}

Answered by @MaximeJ

I’m also wondering why we’re not calling super.init(s0, t) in ImpulseManeuver#init instead of repeating the line forward = t.durationFrom(s0.getDate()) >= 0;