protected function addRenderable(RenderableInterface $renderable)
    {
        if ($renderable->getParentRenderable() !== null) {
            throw new FormDefinitionConsistencyException(sprintf('The renderable with identifier "%s" is already added to another element (element identifier: "%s").', $renderable->getIdentifier(), $renderable->getParentRenderable()->getIdentifier()), 1325665144);
        }
        $renderable->setIndex(count($this->renderables));
        $renderable->setParentRenderable($this);
        $this->renderables[] = $renderable;
    }