public function getRootForm()
    {
        $rootRenderable = $this->parentRenderable;
        while ($rootRenderable !== null && !($rootRenderable instanceof FormDefinition)) {
            $rootRenderable = $rootRenderable->getParentRenderable();
        }
        if ($rootRenderable === null) {
            throw new FormDefinitionConsistencyException(sprintf('The form element "%s" is not attached to a parent form.', $this->identifier), 1326803398);
        }

        return $rootRenderable;
    }