protected function registerAvailableVersions()
    {
        $this->availableVersions = [];
        foreach ($this->packageManager->getAvailablePackages() as $package) {
            $this->registerVersionInDirectory($package, 'TYPO3CR');
            $this->registerVersionInDirectory($package, 'ContentRepository');
        }
        ksort($this->availableVersions);
    }