code: protected function fetchAllPropsForSelect()
      {
          $props = [];
          $rsProps = static::$cIblockObject->GetProperties($this->iblockId);
          while ($prop = $rsProps->Fetch()) {
              $props[] = 'PROPERTY_'.$prop['CODE'];
          }
  
          return $props;
      }
docs: Fetch all iblock property codes from database
  
  return array