### Question:
Order { @Nullable public String getCustomerOrderId() { return customerOrderId; } private  Order(Builder builder); String getId(); @Deprecated long getAmount(); String getCurrencyCode(); Date getPurchaseDate(); List<LineItem> getLineItems(); @Nullable String getCustomerOrderId(); @Nullable Customer getCustomer();  }### Answer:
@Test public void order_setCustomerOrderId_verify() { String customerOrderId = "valid_customer_order_id"; Order order = new Order.Builder("123", new Date(), Collections.<Order.LineItem>emptyList()) .setCustomerOrderId(customerOrderId) .build(); assertEquals(order.getCustomerOrderId(), customerOrderId); }