CachingJPATraversableResolverForSingleValidation is not thread safe because it's not supposed to be. It's used to wrap the underlying TraversableResolver for a single validate call.

It's all done automatically so you do not need to care about this.

I don't know exactly what's happening in your case and it would be hard to say without a reproducer but you can for sure define your own traversable resolver to avoid using the default ones. The JPA one is automatically chosen if you have a JPA implementation around. If you are not validating entities, it's indeed better to avoid using it.

You can find a good example of that in Quarkus for instance:

• https://github.com/quarkusio/quarkus/blob/master/extensions/hibernate-validator/runtime/src/main/java/io/quarkus/hibernate/validator/runtime/HibernateValidatorRecorder.java#L87
• https://github.com/quarkusio/quarkus/blob/master/extensions/hibernate-validator/runtime/src/main/java/io/quarkus/hibernate/validator/runtime/TraverseAllTraversableResolver.java

Also some interesting read in the doc:

• https://docs.jboss.org/hibernate/stable/validator/reference/en-US/html_single/#section-validator-factory-traversable-resolver
• https://docs.jboss.org/hibernate/stable/validator/reference/en-US/html_single/#section-configuration-validation-xml