ActiveMQ... Exceptions Handling

It is strange to see such code in a mature project like ActiveMQ:

   public void onException(JMSException e) {
       if(exceptionListener!=null && managedConnection!=null) {
           try {
               exceptionListener.onException(e);
           } catch (Throwable ignore) {
               // We can never trust user code so ignore any exceptions.
           }
       }
   }

(that was source code from ActiveMQ project)