/** {@inheritDoc} */
 @Override
 public void passivate() {
   if (LOGGER.isDebugEnabled()) {
     LOGGER.debug("passivating output...");
   }
   // Clear all lists and reset the flags.
   listener.clear();
   if (synthesisQueue != null) {
     synthesisQueue.clearQueue();
     synthesisQueue.interrupt();
     synthesisQueue = null;
   }
   if (LOGGER.isDebugEnabled()) {
     LOGGER.debug("...passivated output");
   }
 }