private function validateContentTypes(Bag $importData)
    {
        $contentTypeNames = $this->contentTypes->keys()->toArray();
        $importData->filter(function ($k, $v) use ($contentTypeNames) {
            if (!in_array($k, $contentTypeNames)) {
                throw new RuntimeException(sprintf('ContentType "%s" is not configured.', $k));
            }
        });
    }