Hi Gunnar, thank you for your reply. As for the default package issue I tought that <default-package> in the XML is for the beans that are validated and not for the constraint annotation classes - as the validated bean is Double that's why the default package is set to java.lang, but even if the default package is applied to annotations in case of class not found exception I guess you should try to get the class as it is specified in the XML without prepending the default package specified in the XML - the similar case when the annotation have a package - you will not try to see the java.lang.testvalidation.MyConstraint - e.g prepending java.lang to the class name