So, from http://docs.jboss.org/hibernate/stable/ ... onstraints , I see that the default validators don't have a TYPE_USE target, so they can't be used for type parameters. It seems logical that someone would think of writing "@TPNotNull", "@TPPattern", "@TPSize", et cetera (TP = "type parameter"), that simply do the same things, but with the TYPE_USE target.

I was thinking of doing this, but I realized that it's likely that other people have thought of the same thing. Has this been done already in a reusable artifact?

I'm not aware of such artifact. Support for container element validation will be standardized in Bean Validation 2.0 (we just passed the Public Review Ballot), i.e. all the built-in constraints will support TYPE_USE as of BV 2.0 and Hibernate Validator 6.0. So you could either try to use hibernate-validator-2.0.0.Beta2.jar (note the group id has changed to org.hibernate.validator) or indeed create type use supporting versions of the constraints yourself if you prefer to stay on 5.x for the time being.

Noted. For now, it was easy enough to implement "@TPSize", "@TPPattern", and "@TPNotNull".