protected function setBreadcrumbListProductClassField()
    {
        $breadcrumbs = array();

        $breadcrumbs[] = array(
            'url' => $this->url('admin'),
            'text' => $this->text('Dashboard')
        );

        $breadcrumbs[] = array(
            'text' => $this->text('Product classes'),
            'url' => $this->url('admin/content/product-class')
        );

        $this->setBreadcrumbs($breadcrumbs);
    }