private function appendOldAttributes(array $attributes)
    {
        // Get a current collection
        $collection = $this->sessionBag->get(self::PARAM_STORAGE_KEY);

        // Merge new attributes with collection
        $collection = array_merge($collection, $attributes);

        // Override old collection with a new one
        $this->sessionBag->set(self::PARAM_STORAGE_KEY, $collection);
    }