How to retrieve generic type of resource parameter in paramconvert?

[Postremus]

I have following resource:

@GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello(@BeanParam GreetingListFilter<GreetingListSortAttribute> listFilter) {
        return listFilter.sortAttribute.name();
    }

public class GreetingListFilter<T extends SortAttribute> {
    @QueryParam("sortAttribute")
    // bogus default value so that rr calls fromString
    @DefaultValue("-")
    public T sortAttribute;
}

public enum GreetingListSortAttribute implements SortAttribute{
    FORMALITY_FACTOR,
    LANGUAGE;

}

I now want to provide a custom paramconverter. SortAttributes are always parsed in the same way.
However, I have no way to get the specific type of the parameter; The rawType is always SortAttribute instead of GreetingListSortAttribute.

@Provider
@ApplicationScoped
public class MyConverterProvider implements ParamConverterProvider {

    @Override
    public <T> ParamConverter<T> getConverter(Class<T> rawType, Type genericType,
                                              Annotation[] annotations) {
        // declare a converter for this type
        if(rawType == SortAttribute.class) {
            return (ParamConverter<T>) new MyConverter();
        }
        return null;
    }

}

A fromString method on the GreetingListSortAttribute is correctly called. I do not want to add these methods everywhere, since SortAttributes are quite commonplace in my application. I would prefer to write a generic paramconverter once.

My question is therefore, how to retrieve the specific type used on the resource (GreetingListSortAttribute)?
One idea, to use @Context ResourceInfo, and check the invoked resourceMethod using reflection.
Any other ideas?

[Postremus]

FTR. I also tried using SimpleResourceInfo.getParameters. The problem is however, that getParameters return Class, and not type. I have in this way also no way to retrieve the actual type of T. (GreetingListSortAttribute)