Add custom constraints based on convetion

Currently custom constraints can be added using the Config.groovy class as described inhttp://www.zorched.net/2008/01/26/custom-validators-in-grails-in-a-single-app/

E.g.: org.codehaus.groovy.grails.validation.ConstrainedProperty.registerNewConstraint(
PostalCodeConstraint.POSTAL_CODE_CONSTRAINT, PostalCodeConstraint.class)

I think it would be great if constraints can be added by convention.
E.g. add the PostcodeConstraint to some folder/package (utils?) and that Grails picks it up automatically and registers it. Just like it does it with the Codecs.