For the following interface and class the CDI portable extension doesn't trigger method validation upon invocation of the reverse() method:

public interface Repeater<T> {

	@NotNull
	Object reverse(T in);
}

public class DefaultRepeater implements Repeater<String> {

	@Override
 	public String reverse(String in) {
		return null;
	}
}

The cause seems to be that in ValidationExtension#determineConstrainedMethod() we pass the overridden method from the super-type together with the bean descriptor from the sub-type to isNonGetterConstrained(). As the method signature has a different parameter type in the sub-type (String instead of Object) the meta-data look-up fails and the method is not considered constrained.