/**
  * Return clients IP address.
  *
  * @return string
  */
 private function getClientIp()
 {
     if ($this->configuration->getXForwardedFor() && isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
         return $_SERVER['HTTP_X_FORWARDED_FOR'];
     }
     return $_SERVER['REMOTE_ADDR'];
 }