+ 'classes' => $classes,
+ 'group' => new OOUI\StackLayout( [
+ 'expanded' => false,
+ 'classes' => [ 'oo-ui-fieldsetLayout-group mw-collapsible-content' ],
+ 'items' => [
+ new OOUI\Widget( [
+ 'content' => new OOUI\HtmlSnippet( $html )
+ ] ),
+ ],
+ ] ),