public function setCashItems($items)
    {
        $this->params['cashItems'] = base64_encode(
            json_encode(
                array_map(function ($item) {
                    /** @var CashItem $item */
                    return array(
                        'name'  => $item->getName(),
                        'count' => $item->getCount(),
                        'price' => $item->getPrice()
                    );
                }, $items)));

        return $this;
    }