public function getContentTypesByGroup($identifier)
    {
        $contentTypesCollection = array();

        if ($contentTypeGroupIdentifier = $identifier) {
            $contentTypeGroup = $this->contentTypeService->loadContentTypeGroupByIdentifier($contentTypeGroupIdentifier);
            $contentTypesCollection = $this->contentTypeService->loadContentTypes($contentTypeGroup);
        }

        return $contentTypesCollection;
    }