public GroupingOptions<G> setGroupComparator(final Comparator<G> groupComparator, final boolean sortGroupsBeforeItems) {
            this.groupComparator = groupComparator;
            this.sortGroupsBeforeItems = sortGroupsBeforeItems;
            triggerChange(ChangeType.COMPLETE);
            return this;
        }
Sets a cgroups are sorted and where items are sorted in reference to groups
main/src/main/java/cgeo/geocaching/ui/SimpleItemListModel.java