public Model downgradeEnums(Model model) {
        return ChangeShapeType.downgradeEnums(model).transform(this, model);
    }
Changes each enum shape to a string shape and each intEnum to an integer.

@param model Model to transform.
@return Returns the transformed model.
smithy-model/src/main/java/software/amazon/smithy/model/transform/ModelTransformer.java