protected function getActiveSitePackageKeys()
    {
        $sitePackages = $this->packageManager->getFilteredPackages('available', null, 'neos-site');
        $result = [];
        foreach ($sitePackages as $sitePackage) {
            $packageKey = $sitePackage->getPackageKey();
            $result[] = $packageKey;
        }
        return $result;
    }