public GroupingTransform putMax(int tag, int max, String type) {
        if (maxes.containsKey(tag)) {
            throw new IllegalStateException("Can not set max of " + type + " " + tag + " to " + max +
                                            " because it is already set to " + maxes.get(tag) + ".");
        }
        maxes.put(tag, max);
        return this;
    }
This class contains enough information about how a {@link com.yahoo.search.grouping.request.GroupingOperation} was
transformed into a list {@link com.yahoo.searchlib.aggregation.Grouping} objects, so that the results of those
queries can be transformed into something that corresponds to the original request.

@author Simon Thoresen Hult
container-search/src/main/java/com/yahoo/search/grouping/vespa/GroupingTransform.java