private static function cachingPartial($actionContext, $eventArgs) {
        $cacheKey = InternalHelper::getPropertyValue($actionContext, 'cacheKey');

        // no key, no cache
        if (empty($cacheKey)) {
            return;
        }

        $cache = $httpContext->getCache();
        $cachePartSeq = $cache->get($cacheKey . '_part_seq');

        if (!isset($cachePartSeq)) {
            $cachePartSeq = -1;
        }

        $dataToCache = array();
        $dataToCache['output'] .= $eventArgs['output'];
        $dataToCache['files'] = array_merge($dataToCache['files'], $eventArgs['files']);

        $cache->add($cacheKey . '_part_' . $cachePartSeq, $dataToCache, 30);
        $cache->add($cacheKey . '_part_seq', (int)$cachePartSeq + 1, 30);
    }