code: private void doGroupEnd(final JsonObject message) {
      String groupID = message.getString("group");
      DefaultConnectionInputGroup group = groups.remove(groupID);
      if (group != null) {
        Object args = deserializer.deserialize(message);
        if (log.isDebugEnabled()) {
          log.debug(String.format("%s - Group ended: Group[group=%s, args=%s]", this, group.id(), args));
        }
        group.handleEnd(args);
      }
    }
docs: Handles a group end.