Sort Group Ascendingly(asc_max) by Max Value in Each Group

Solr group supports asc and desc on some field:
let's take sort=time asc as an example
In asc mode: groups are sorted by the min value in the group,
In desc mode, groups are sorted by the max value in the group.

But users may want more:
in asc_max mode, sort group by max(not min) value in the group
==> this should be a common requirement.
Vice verse, in desc_min mode, sort group by min(not max) value in th group.

We have this requirement in our product, and we implemented in some cumbersome way: by create a new kind of FieldComparator: LongAbnormalComparator

It would be great Solr can support this.