CDI extension provided in Hibernate Validator jar should sometimes not be activated depending of the environment, as it could interact with other components.
Hibernate Validator should provide a way to deactivate it's own provided extension to prevent unwanted interaction if necessary.
Have a look to org.apache.deltaspike.core.spi.activation.ClassDeactivator in the Apache Delta Spike project. The same mechanism could be replicated to implement this feature, or maybe Hibernate Validator could depend on Delta Spike?
see also forum reference - https://community.jboss.org/message/804247