protected function renderHiddenReferrerFields()
    {
        $tagBuilder = new TagBuilder('input');
        $tagBuilder->addAttribute('type', 'hidden');
        $tagBuilder->addAttribute('name', $this->prefixFieldName('__state'));
        /** @var FormRuntime $formRuntime */
        $formRuntime = $this->arguments['object'];
        $tagBuilder->addAttribute('value', $formRuntime->getSerializedFormState());
        return $tagBuilder->render();
    }