public function __construct($publicKey, $locale = null)
 {
     if (null === $publicKey) {
         throw new InvalidConfigurationException('The parameters "public_key" must be configured.');
     }
     $this->publicKey = $publicKey;
     if (null !== $locale) {
         $this->locale = $locale;
     } else {
         $this->locale = Locale::getDefault();
     }
 }