default void triggerHapticAction( String actionName, float duration, float frequency, float amplitude){
       triggerHapticAction( actionName, duration, frequency, amplitude, null );
   }
Triggers a haptic action (aka a vibration).

Note: if you want a haptic action in only one hand, you can either bind the action to one hand in
the action manifest's standard bindings or bind to both and use
{@link #triggerHapticAction(String, float, float, float, String)}
to control which input it gets set to at runtime.

@param actionName The name of the action. Will be something like /actions/main/out/vibrate
@param duration how long in seconds the
@param frequency in cycles per second
@param amplitude between 0 and 1
jme3-vr/src/main/java/com/jme3/input/vr/VRInputAPI.java