public function getWhitelistServerParameters()
 {
     if ($this->whitelistServerParameters == null) {
         $this->whitelistServerParameters = $this->retrieveWhitelistParameters($this->configuration->parameters->server);
         if (empty($this->whitelistServerParameters)) {
             $this->whitelistServerParameters = parent::getWhitelistServerParameters();
         }
     }
     return $this->whitelistServerParameters;
 }