code: void doGroupEnd(String group, Object args) {
      checkOpen();
      JsonObject message = createMessage(args)
          .putString("action", "endGroup")
          .putString("group", group);
      if (open && !paused) {
        if (log.isDebugEnabled()) {
          log.debug(String.format("%s - Group end: Group[group=%s, args=%s]", this, group, args));
        }
        eventBus.send(inAddress, message);
      }
      groups.remove(group);
    }
docs: Sends a group end message.