Just to help any other coming here for this error.
This is not an error but it's the way Hibernate works. If no custom TraversableResolver is configured, the default one is used (DefaultTraversableResolver), which inspects about all JPA2 providers in the system and, if any of them are found, use them in order to check if a bean can be validated or not through the class JPATraversableResolver.

The problem comes when a JPA2 provider is found which doesn't implement all methods (some abstract) from JPA2 that are used by the JPATraversableResolver.

Please read this documentation: http://docs.jboss.org/hibernate/validator/4.0.1/reference/en/html/validator-bootstrapping.html#d0e2255

You can workaround the problem defining your own TraversableResolver with all its methods returning true through the file META-INF/validation.xml like this:

<validation-config
    xmlns="http://jboss.org/xml/ns/javax/validation/configuration"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://jboss.org/xml/ns/javax/validation/configuration">
    <traversable-resolver>yourpackage.CustomTraversableResolver</traversable-resolver>
</validation-config>