code: public void unsubscribe() {
          final long id = Thread.currentThread().getId();
          queues.remove(id);
          if (subscriberIdentifiers != null) {
              for (Iterator<Entry<Object, Long>> iterator = subscriberIdentifiers.entrySet().iterator(); iterator.hasNext(); ) {
                  if (id == iterator.next().getValue()) {
                      iterator.remove();
                      break;
                  }
              }
          }
      }
docs: Unsubscribes the thread from the queue.