private HitOrderer dirtyCopyIfModifiedOrderer(HitGroup group, HitOrderer orderer) {
        if (orderer != null) {
            HitOrderer old = group.getOrderer();
            if (! orderer.equals(old)) {
                group.setOrderer(orderer);
            }
        }

        return orderer;
    }
TODO This is probably a dirty hack for bug 4711376. There are probably better ways.
But I will leave that to trd-processing@

@param group the merging hitgroup to be updated if necessary
@param orderer the per provider hit orderer
@return he hitorderer chosen
container-search/src/main/java/com/yahoo/search/federation/FederationSearcher.java