[bv-dev] Method Validation: Why Example 4.11 should be allowed

I think there is a general problem with the application of this rule: "a method's preconditions (as represented by parameter constraints) may not be strengthened in sub types" The problem is that this could hurt API developers who publish basic interfaces but where implementation designers are free to choose validations specific to their system. Example 4.11 is a great example: public interface OrderService { void placeOrder(String customerCode, Item item, int quantity); } public class SimpleOrderService implements OrderService { @Override public void placeOrder( @NotNull @Size(min=3, max=20) String customerCode, @NotNull Item item, @Min(1) int quantity) { ... } } I can see no good reason why this should be disallowed. The spec is assuming that because no constraints are on the interface, no implementation may ever use constraints. This is a poor assumption. It is actually a blockade to any system that currently exists -- being created prior to BeanValidation -- who could benefit from adding method-level validation in their implementation. This can be easily corrected though. Apply these rules only on concrete classes. If SimpleOrderService2 extends SimpleOrderService, then spec should disallow the strengthening of constraints. In summary, don't consider interfaces (unless the interfaces themselves have annotated constraints?). Do you see the problem I am addressing? Thanks, Paul