public Model changeStringEnumsToEnumShapes(Model model) {
        return ChangeShapeType.upgradeEnums(model, false).transform(this, model);
    }
Changes each compatible string shape with the enum trait to an enum shape.

<p>A member will be created on the shape for each entry in the {@link EnumTrait}.

<p>Strings with enum traits that don't define names are not converted.

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