I've experimented a bit with the BV API and I'm quite happy with it but I find the way to pass back metadata along with the error a bit limiting, if payloads is an array of static classes that can lead to an explosion of classes, it would have been nice if simple static things like list of enums or strings or numbers would have been allowed as well.
Ex, I'd like to assign a specific error code to an validation exception which doesn't have anything to do with the error message but will be used programmatically?
Ex. @NotNull(message="my_custom_not_null_key", payload={"Code._12345"})

Hi,

The problem is that one cannot design an annotation attribute such as payload() in a way that it can take an enum OR a String OR an int etc. Thus we went for the class-based approach.

In your case you may be able to use the message() property in a somewhat creative way by working with a defined format of messages; E.g. in the form "code#key" with "12345#my_custom_not_null_key" being one specific message. You could then implement a custom message interpolator (https://docs.jboss.org/hibernate/stable/validator/reference/en-US/html_single/#section-custom-message-interpolation) which only considers the key part of the messages for interpolation, whereas the code part may be accessed by your other programmatic logic.

Hth,

--Gunnar