docs: public void cancel()
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.entry(tc, "cancel", toString());  
      
      //flag this alarm as canceled (we don't remove it from the list immediately,
      // we leave it to be picked up by the alarm thread)
      active = false;
      
      // If this is a GroupAlarmListener it supports a cancel method, that we can call
      if(groupListener && (data != null))
        ((GroupAlarmListener)data).cancel();
  
      // Forget about the registered listener object and context
      data = null;
      groupListener = false;
      context = null;
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.exit(tc, "cancel");
    }