public function requireOnce(string $entryIdentifier)
    {
        $pathAndFilename = $this->cacheDirectory . $entryIdentifier . $this->cacheEntryFileExtension;
        if ($entryIdentifier !== basename($entryIdentifier)) {
            throw new \InvalidArgumentException('The specified entry identifier (' . $entryIdentifier . ') must not contain a path segment.', 1282073036);
        }

        if (is_file($pathAndFilename)) {
            return include_once($pathAndFilename);
        }
        return false;
    }