private static Model scopeModelToService(Model model, ShapeId serviceId) {
        if (serviceId == null) {
            return model;
        }
        Set<Shape> connected = new Walker(model).walkShapes(model.expectShape(serviceId));
        return ModelTransformer.create().filterShapes(model, connected::contains);
    }
A workaround for including definitions for Unit; it's only included in the schema if a union targets it.
smithy-jsonschema/src/main/java/software/amazon/smithy/jsonschema/JsonSchemaConverter.java