code: private SortedQueue getQueueReadOnly(String queueName, Duration waitDuration) {
          DedupQueue service = getQueueReadWrite(queueName, waitDuration);
          if (service != null) {
              try {
                  return service.getQueue();
              } catch (ReadOnlyQueueException e) {
                  // Fall through
              }
          }
          return _sortedQueueFactory.create(queueName, true, _queueDAO);
      }
docs: Returns the persistent sorted queue managed by this JVM, or a stub that supports only read-only operations if
  not managed by this JVM.