private boolean sortableWithSortData() {
        return hitsWithSortData > 0 && hitsWithSortData == concreteHitCount;
    }
Force hit sorting now.
This is not normally useful because a group will stay sorted automatically,
but it is in the case where
the hits have changed their internal state in a way that should change ordering
container-search/src/main/java/com/yahoo/search/result/HitGroup.java