code: protected void connect() {
      LOG.info("Connecting to collector...");
      try {
        conf.setStrings(UnixUserGroupInformation.UGI_PROPERTY_NAME,
                        new String[]{"hadoop", "hadoop"});
        rpcCollector =
              (UtilizationCollectorProtocol) RPC.getProxy(UtilizationCollectorProtocol.class,
                                               UtilizationCollectorProtocol.versionID,
                                               UtilizationCollector.getAddress(conf),
                                               conf);
      } catch (IOException e) {
        LOG.error("Cannot connect to UtilizationCollector server. Retry in " +
                 DEFAULT_MIRROR_PERIOD + " milliseconds.");
        return;
      }
      LOG.info("Connection established");
    }
docs: Make connection to the Collector