PayCart payCart = PayCart.builder()
  .merchantName(MERCHANT_NAME)
  .currencyCode(shop.currency)
  .shippingAddressRequired(checkout.requiresShipping)
  .phoneNumberRequired(true)
  .shipsToCountries(Arrays.asList("US", "CA"))
  .addLineItem("Product1", 1, BigDecimal.valueOf(1.99))
  .addLineItem("Product2", 10, BigDecimal.valueOf(3.99))
  .subtotal(checkout.subtotalPrice)
  .totalPrice(checkout.totalPrice)
  .taxPrice(checkout.taxPrice)
  .build();