/**
  * @return \service\certificates\Client
  */
 public static function getWebserviceClient()
 {
     if ( !isset(self::$wsClient) )
     {
         // Guzzle RESTclient
         $builder        = ServiceBuilder::factory(__DIR__ . '/../descriptor.php');
         self::$wsClient = $builder['certificates'];
     }
     return self::$wsClient;
 }