It's currently not clearly specified, whether buildValidatorFactory() may be invoked several times on a given Configuration instance. A use case for this might be to create several factories which only slightly differ in their configuration:
We should explicitly mention whether that's allowed or not.
Related discussion on the mailing list: http://lists.jboss.org/pipermail/beanvalidation-dev/2012-March/000290.html
Related post in HV forum: https://forum.hibernate.org/viewtopic.php?f=9&t=1014788