code: private MessageProducer getProducer(final String destinationName) {
  
  
          if (!producers.containsKey(destinationName)) {
  
              Session session = getSession();
              Destination destination = getDestination(destinationName);
              MessageProducer producer;
              try {
                  producer = session.createProducer(destination);
              } catch (JMSException e) {
                  throw new JmsException("Unable to create producer for destination "
                          + destinationName, e);
              }
              producers.put(destinationName, producer);
  
          }
          return producers.get(destinationName);
      }
docs: Get the `MessageProducer` or create one from the JMS session.
  
  @param destinationName destinationName
  @return JMS `MessageProducer`.