@Override
    public void showFilterMenu() {
        FilterUtils.openFilterActivity(this, mapOptions.filterContext,
                new SearchResult(caches.getVisibleCacheGeocodes()).getCachesFromSearchResult(LoadFlags.LOAD_CACHE_OR_DB));
    }
initialization with an empty subscription to make static code analysis tools more happy
main/src/main/java/cgeo/geocaching/maps/mapsforge/v6/NewMap.java