Hibernate Validator can be upgraded to the latest stable: Hibernate Validator 5.3.2.Final.
API wise, there are very few changes except to features that were experimental.
WildFly is currently using 5.2.4.Final.
Changes from 5.2.4.Final to 5.3.2.Final:
- bugfixes, some of them are only available in the 5.3.x branch so they are by themselves a good reason to upgrade;
- the ability to add dynamic payloads to contraint violations. See http://in.relation.to/2016/01/18/hibernate-validator-530-alpha1-out/ for more information.
- a new programmatic API for constraint definition and declaration: it replaces an experimental feature with something more consistent with the rest of Hibernate Validator APIs. See http://in.relation.to/2016/09/05/hibernate-validator-530-cr1-out/ for more information
- new translations of the builtin constraints messages
- various improvements to the OSGi support
- various improvements to the JDK 9 support
Migration guide for 5.3 outlining the changes requiring attention when upgrading: https://developer.jboss.org/wiki/HibernateValidatorMigrationGuide#jive_content_id_53x
I'm working on validating the upgrade in WildFly and preparing a PR.