.withImplementation(ModelType.of(DefaultThingSpec))
            .withInternalView(ModelType.of(ThingSpecInternal))
        instanceFactory.register(ModelType.of(ManagedThingSpec), new SimpleModelRuleDescriptor("managed"))
            .withInternalView(ModelType.of(ManagedThingSpecInternal))

        if (implementationType != null) {
            registration.withImplementation(implementationType);
        }
        for (Class<?> internalView : internalViews) {
            registration.withInternalView(ModelType.of(internalView));
        }
    }

    /**
     * Registers a factory to use to create all implementation objects of the given type and its subtypes. The most specific match is used.
     */