protected function initializeUrlRewriteProductCategory($attr)
    {

        // try to load the URL rewrite product category relation
        if ($urlRewriteProductCategory = $this->loadUrlRewriteProductCategory($attr[MemberNames::URL_REWRITE_ID])) {
            return $this->mergeEntity($urlRewriteProductCategory, $attr);
        }

        // simple return the URL rewrite product category
        return $attr;
    }