protected function loadContentTypeByIdentifier($identifier, $throwIfNotFound = true)
    {
        $contentType = null;
        try {
            $contentType = $this->contentTypeService->loadContentTypeByIdentifier($identifier);
        } catch (ApiExceptions\NotFoundException $e) {
            $notFoundException = $e;
        }

        if (!$contentType && $throwIfNotFound) {
            throw $notFoundException;
        }

        return $contentType;
    }