public function resolveAction($action)
    {
        if (!array_key_exists($action, self::$frontendHelperRegistry)) {
            return null;
        }

        $frontendHelper = GeneralUtility::makeInstance(self::$frontendHelperRegistry[$action]);
        if (!$frontendHelper instanceof FrontendHelper) {
            $message = self::$frontendHelperRegistry[$action] . ' is not an implementation of ApacheSolrForTypo3\Solr\IndexQueue\FrontendHelper\FrontendHelper';
            throw new \RuntimeException($message, 1292497896);
        }

        $this->activatedFrontendHelpers[$action] = $frontendHelper;
        return $frontendHelper;
    }