3 declare(strict_types=1);
    15     $factory = $DIC->ui()->factory();
    16     $renderer = $DIC->ui()->renderer();
    17     $request = $DIC->http()->request();
    19     $optional_group = $factory->input()->field()->optionalGroup([
    20         $factory->input()->field()->text(
    21             'this input is required',
    22             'but only if the optional group is checked'    24     ], 
'this input is not required');
    26     $form = $factory->input()->container()->form()->standard(
'#', [$optional_group]);
    28     if (
"POST" === $request->getMethod()) {
    29         $form = $form->withRequest($request);
    30         $result = $form->getData();
    32         $result = 
"No result yet.";
    35     return "<pre>" . print_r($result, 
true) . 
"</pre>" . $renderer->render($form);