public function addInstallmentCheckoutPreferences($quantity, $discountValue = 0, $additionalValue = 0)
    {
        $installmentPreferences = new stdClass();
        $installmentPreferences->quantity = $quantity;
        $installmentPreferences->discount = $discountValue;
        $installmentPreferences->addition = $additionalValue;

        $this->data->checkoutPreferences->installments[] = $installmentPreferences;

        return $this;
    }