code: private static String lookupHost(Properties props) {
          String host = null;
  
          // 1. lookup system property 'td.logger.api.server.host'
          if (props.containsKey(Config.TD_LOGGER_API_SERVER_HOST)) {
              host = props.getProperty(Config.TD_LOGGER_API_SERVER_HOST);
          }
  
          // if not exists, set default value
          if (host == null) {
              host = Config.TD_LOGGER_API_SERVER_HOST_DEFAULT;
          }
  
          // write/overwrite it to 'td.api.server.host'
          props.setProperty(Config.TD_API_SERVER_HOST, host);
          return host;
      }
docs: Define order for hostname lookup.
  1. lookup props's td.logger.api.server.host