For groupRenderStrategy=multiple this is quite easy, as sorting by it will in fact sort by the corresponding grouping.
For groupRenderStrategy=single, it's not that difficult either, as it should behave as if it had multiple sorts - one for each groupBy field.
For groupRenderStrategy=multiple this is quite easy, as sorting by it will in fact sort by the corresponding grouping. For groupRenderStrategy=single, it's not that difficult either, as it should behave as if it had multiple sorts - one for each groupBy field.