Hibernate Validator: Correctly detect custom ValueExtractor beans

[yrodiere]

Fixes #20347 , though not completely: there are still limitations, reported as #20375 and #20377 .

So for now, custom ValueExtractor beans will only work properly if they are annotated with @Singleton, and perhaps @Dependent; they definitely won't work if annotated with @ApplicationScoped (because of #20375).

[yrodiere]

This is the only way I found to select all beans implementing ValueExtractor<Something>.

Strangely, .select(ValueExtractor.class) does not match a bean implementing ValueExtractor<List<?>>, for example.

I say strangely, because you can definitely assign ValueExtractor<List<?>> to a variable of type ValueExtractor (the raw type). So if you consider that .select(ValueExtractor.class) should select all beans that can be assigned to ValueExtractor (the raw type), then beans implementing ValueExtractor<List<?>> should definitely be selected.

But no, that's not how it works, apparently.

According to the javadoc on io.quarkus.arc.impl.BeanTypeAssignabilityRules#matches(java.lang.Class<?>, java.lang.reflect.ParameterizedType):

     * A parameterized bean type is considered assignable to a raw required type if the raw types are identical and all type
     * parameters of the bean type are
     * either unbounded type variables or java.lang.Object.

So according to this definition, ValueExtractor<T> is assignable to ValueExtractor, but ValueExtractor<List<?>> is not.

@stuartwdouglas is this on purpose? Or should we adjust the implementation of io.quarkus.arc.impl.BeanTypeAssignabilityRules#matches(java.lang.Class<?>, java.lang.reflect.ParameterizedType)?

[stuartwdouglas]

This is a question for @mkouba, but this sounds like a bug.

[yrodiere]

Ok, sorry for the noise. Created #20410 for @mkouba :)

[mkouba]

This works as required by the spec: "A parameterized bean type is considered assignable to a raw required type if the raw types are identical and all type parameters of the bean type are either unbounded type variables or java.lang.Object"; see also https://docs.jboss.org/cdi/spec/2.0/cdi-spec.html#assignable_parameters