@Override
    public void setId(URI id) {
        super.assignId(id);
    }
Assign an id to this hit.
For HitGroups, this is a legal call also when an id is already set,
i.e hit groups allows their ids to be reassigned.
This is to allow hit groups to be inserted in new structures with an id reflecting their
role/placement in the structure.

@param id the new or initial iof of this hit
container-search/src/main/java/com/yahoo/search/result/HitGroup.java