kekrozsak/vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Resources/views/Form/widget_container_attributes.html.php

<?php if (!empty($id)): ?>id="<?php echo $view->escape($id) ?>" <?php endif; ?>
<?php foreach ($attr as $k => $v) { printf('%s="%s" ', $view->escape($k), $view->escape($v)); } ?>