code: public String obtainLoopbackIp4Address() {
      final NetworkInterface networkInterface = getLoopBackAndIp4Only();
      if (networkInterface != null) {
        return networkInterface.getIp4LoopbackOnly().getHostName();
      }
  
      final String ipOfIp4LoopBack = getIpOfLoopBackIp4();
      if (ipOfIp4LoopBack != null) {
        return ipOfIp4LoopBack;
      }
  
      if (Platform.getCurrent().is(Platform.UNIX)) {
        NetworkInterface linuxLoopback = networkInterfaceProvider.getLoInterface();
        if (linuxLoopback != null) {
          final InetAddress netAddress = linuxLoopback.getIp4LoopbackOnly();
          if (netAddress != null) {
            return netAddress.getHostAddress();
          }
        }
      }
  
      throw new WebDriverException(
          "Unable to resolve local loopback address, please file an issue with the full message of this error:\n"
              +
              getNetWorkDiags() + "\n==== End of error message");
    }
docs: Returns a single address that is guaranteed to resolve to an ipv4 representation of localhost
  This may either be a hostname or an ip address, depending if we can guarantee what that the
  hostname will resolve to ip4.
  
  @return The address part og such an address