public function setInstanceCriteriaFilter()
 {
     if (self::$s_criteria_filter == null) {
         self::$s_criteria_filter = new criteriaFilter();
     }
     $c = self::$s_criteria_filter->getFilter();
     if ($c) {
         $c->remove(self::DELETED_AT);
         $c->remove(self::TYPE);
     } else {
         $c = new Criteria();
     }
     $c->add(self::DELETED_AT, null, Criteria::EQUAL);
     $c->add(self::TYPE, assetType::THUMBNAIL, Criteria::NOT_EQUAL);
     self::$s_criteria_filter->setFilter($c);
 }