public function onGetDatabaseResources(GetDatabaseResourcesEvent $event)
    {
        // prevent errors on command such as cache:clear if doctrine schema has not been updated yet
        if (StorageInterface::STORAGE_ORM == $this->storageType && !$this->storage->translationsTablesExist()) {
            $resources = array();
        } else {
            $resources = $this->storage->getTransUnitDomainsByLocale();
        }

        $event->setResources($resources);
    }