Observer resolution - assignability clarification ------------------------------------------------- Key: CDI-736 URL: https://issues.jboss.org/browse/CDI-736 Project: CDI Specification Issues Issue Type: Clarification Components: Resolution Affects Versions: 2.0.SP1 Reporter: Matej Novotny Fix For: 2.1 (Discussion) Recently we came up across an observer resolution issue which concerns [10.3.1. Assignability of type variables, raw and parameterized types|http://docs.jboss.org/cdi/spec/2.0/cdi-spec.html#observers_assignab...]. What happens when you are trying to assign a non-parameterized subclass to a parameterized superclass? Here is a bit of code, we have following two classes: {code} public interface QualifiedEvent<T> { // some methods } public class EventImpl implements QualifiedEvent { //NOTE - implements raw type // some method impls } {code} Here is observer code: {code} void listenForChildEvent(@Observes QualifiedEvent<Bar> foo) { // stuff going on here... } {code} And your event type is: {code} new EventImpl(clazz); {code} In this scenario, the spec is IMO unclear on what should happen in this particular case. Looking at other parts of spec, we already have this covered in, for instance, [delegate injection point assignability|http://docs.jboss.org/cdi/spec/2.0/cdi-spec.html#delegate_a...], where it says: bq. A raw bean type is considered assignable to a parameterized delegate type if the raw types are identical and all type parameters of the delegate type are either unbounded type variables or java.lang.Object. I think we should add a similar sentence to [10.3.1. Assignability of type variables, raw and parameterized types|http://docs.jboss.org/cdi/spec/2.0/cdi-spec.html#observers_assignab...]. That way the spec will behave coherently and *the above observer/event assignability should not work*. Side note - for the sample above to work, you would need to change the observed types to {{QualifiedEvent<?>}}.