Symfony DomCrawler无法获取属性

Question

对于此div：

<section class='menu'>
    <div class="some beautiful classes" link="/some/path/in/web">
        <div class="contImgHome">
            <img src="/images/icon.jpg alt="">
        </div>
        <h5>
            <a href="javascript:void(0);">Go to Section</a>
        </h5>
    </div>
    <div class="some beautiful classes" link="/another/path/in/web">
        <div class="contImgHome">
            <img src="/images/icon.jpg alt="">
        </div>
        <h5>
            <a href="javascript:void(0);">Go to another section</a>
        </h5>
    </div>
</section>

我做的是：

$response = $guzzleClient->request('GET', $url_base);

$crawler = new Crawler( (string) $response->getBody() );
$crawler->filter('section.menu > div')->each(function( Crawler $div, $i )
{
    $xx = $div->extract( [ 'class', 'link'] );

    print_r( $xx );
    echo PHP_EOL;
    die;

});

并返回以下内容：

Array
(
    [0] => Array
        (
            [0] => some beautiful classes
            [1] =>
        )

)

我还尝试了：

$div->attr('classes');
$div->attr('link');

但“link”属性始终为空。#为什么我不能获取link属性？

我使用的是Laravel 5.2，安装了Symfony Crawler vía composer。