code: public synchronized void onComplete() {
  
      LOG.entering(CLASS_NAME, "onComplete");
  
      if (this.isClosing()) {
        LOG.log(Level.WARNING, "Ignoring second call to onComplete()",
            new Exception("Dummy exception to get the call stack"));
      } else {
  
        LOG.log(Level.INFO, "Clean shutdown of the Driver.");
  
        if (LOG.isLoggable(Level.FINEST)) {
          LOG.log(Level.FINEST, "Call stack: ",
              new Exception("Dummy exception to get the call stack"));
        }
  
        this.clock.close();
        this.setStatus(DriverStatus.SHUTTING_DOWN);
      }
  
      LOG.exiting(CLASS_NAME, "onComplete");
    }
docs: Perform a clean shutdown of the Driver.