code: public static NetworkInterface getNetworkInterface(Config config, String path) {
          NetworkInterface value = getNetworkInterfaceByName(config, path);
          if (value == null)
              value = getNetworkInterfaceByInetAddress(config, path);
  
          if (value == null)
              throw badValue("No network interface for value '" + config.getString(path) + "'", config, path);
  
          return value;
      }
docs: Get a network interface. The network interface can be identified by its
  name or its IP address.
  
  @param config a configuration object
  @param path the path expression
  @return a network interface
  @throws ConfigException.Missing if the value is absent or null
  @throws ConfigException.WrongType if the value is not convertible to
  a string
  @throws ConfigException.BadValue if the value cannot be translated
  into a network interface