synchronized public void stopWarrant(boolean abort){
  if (_nextSignal != null) {
    _nextSignal.removePropertyChangeListener(this);
    _nextSignal=null;
  }
  super.stopWarrant(abort);
}

synchronized public void stopWarrant ( boolean abort ) { if ( _nextSignal != null ) { _nextSignal . removePropertyChangeListener ( this ) ; _nextSignal = null ; } super . stopWarrant ( abort ) ; }
make sure to free up additional resources for a running scwarrant .
