private function _run()
 {
     if ($this->predefinedId) {
         $widgetCounter = $this->predefinedId;
     } else {
         $widgetCounter = Counter::getInstance()->getNext();
     }
     /* update parameters in case of any changes */
     foreach ($this->validParameters as $parameter) {
         if (isset($this->{$parameter})) {
             $this->parameters[$parameter] = $this->{$parameter};
         }
     }
     global $baseUrl;
     $json = file_get_contents("{$baseUrl}/list-api.php?" . http_build_query($this->parameters));
     $response = json_decode($json, true);
     $this->widget = new TListWidget($response, $widgetCounter);
 }