code: void doGroupSend(String group, Object value) {
      checkOpen();
      JsonObject message = createMessage(value)
          .putString("action", "group")
          .putString("group", group);
      if (open && !paused) {
        if (log.isDebugEnabled()) {
          log.debug(String.format("%s - Group send: Group[group=%s, id=%d, message=%s", this, group, message.getLong("id"), value));
        }
        eventBus.send(inAddress, message);
      }
      for (OutputHook hook : hooks) {
        hook.handleSend(value);
      }
      checkFull();
    }
docs: Sends a group message.