Jaxb2Marshaller with contextPaths not using ObjectFactory?

[ach]

Currently I have my Web Service Endpoint methods defined like so:

public @ResponsePayload SomeResponseObject getFoo(@RequestPayload SomeRequestObject request) {
  //...
}

My (partial) configuration looks like this:

    @Bean
    public Jaxb2Marshaller marshaller() {
        Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
        marshaller.setContextPaths("com.mycompany.package1", "com.mycompany.package2", "com.mycompany.package3");
        marshaller.setSchemas(schemaLocations());
        return marshaller;
    }

    @Bean
    public MessageDispatcher messageDispatcher() {
        SoapMessageDispatcher dispatcher = new SoapMessageDispatcher();
        dispatcher.setEndpointAdapters(Collections.<EndpointAdapter>singletonList(endpointAdapter()));
        return dispatcher;
    }


    @Bean
    public EndpointAdapter endpointAdapter() {
        DefaultMethodEndpointAdapter adapter = new DefaultMethodEndpointAdapter();
        MarshallingPayloadMethodProcessor processor = new MarshallingPayloadMethodProcessor(marshaller());
        adapter.setMethodArgumentResolvers(Collections.<MethodArgumentResolver>singletonList(processor));
        adapter.setMethodReturnValueHandlers(Collections.<MethodReturnValueHandler>singletonList(processor));
        return adapter;
    }

I thought that since I'm defining my Marshaller with contextPaths, the ObjectFactory classes located in those packages would be used for object creation. However, when I place breakpoints there it doesn't seem to be the case. Why is that, and is there a way to ensure that ObjectFactory is used? I need to do this so that I can force instantiation of some custom extension classes instead of the base generated classes.