public static void createGroupingRequestIn(Query query, GroupingOperation operation, List<Continuation> continuations) {
        GroupingRequest request = GroupingRequest.newInstance(query);
        request.setRootOperation(operation);
        request.setTimeZone(getTimeZone(query.properties().getString(PARAM_TIMEZONE, "utc")));
        request.continuations().addAll(continuations);
    }
This searcher is responsible for turning the "select" parameter into a corresponding {@link GroupingRequest}. It will
also parse any "timezone" parameter as the timezone for time expressions such as {@link
com.yahoo.search.grouping.request.DayOfMonthFunction} and {@link com.yahoo.search.grouping.request.HourOfDayFunction}.

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