when:
        registry.configure(targetRole, ModelReference.of("thing", Bean), Actions.doNothing())

        then:
        def ex = thrown IllegalStateException

            .unmanagedInstance(ModelReference.of(path, type), factory)
            .descriptor(instanceDescriptorFor(path))
            .hidden(true)
            .build());
    }

    private <T> void registerServiceOn(ModelRegistry modelRegistry, String path, ModelType<T> type, T instance, String descriptor) {
        modelRegistry.register(ModelRegistrations.serviceInstance(ModelReference.of(path, type), instance)