protected function initialize()
    {
        $this->data = new stdClass();
        $this->data->ownId = null;
        $this->data->amount = new stdClass();
        $this->data->amount->currency = self::AMOUNT_CURRENCY;
        $this->data->amount->subtotals = new stdClass();
        $this->data->items = [];
        $this->data->receivers = [];
        $this->data->checkoutPreferences = new stdClass();
        $this->data->checkoutPreferences->redirectUrls = new stdClass();
        $this->data->checkoutPreferences->installments = [];
    }