code: private static String lookupPort(Properties props) {
          String port = null;
  
          // 1. lookup system property 'td.logger.api.server.port'
          if (props.containsKey(Config.TD_LOGGER_API_SERVER_PORT)) {
              port = props.getProperty(Config.TD_LOGGER_API_SERVER_PORT);
          }
  
          // if not exists, set defualt value
          if (port == null) {
              port = Config.TD_LOGGER_API_SERVER_PORT_DEFAULT;
          }
  
          // write/overwrite it to 'td.api.server.port'
          props.setProperty(Config.TD_API_SERVER_PORT, port);
          return port;
      }
docs: Define order for port num lookup.
  1. lookup props's td.logger.api.server.port