The reference documentation mentions:
Hibernate Validator provides two TraversableResolvers out of the box which will be enabled automatically depending on your environment. The first is the DefaultTraversableResolver which will always return true for isReachable() and isTraversable(). The second is the JPATraversableResolver which gets enabled when Hibernate Validator gets used in combination with JPA 2.
However, the implementation of DefaultTraversableResolver contains:
It therefore always uses the JPATraversableResolver when JPA is detected.