private String flushMapChanges() {

        final int layersSize = markerLayersForRefresh.size();

        //populate and update marker layers which were touched
        for (int markerZLevelToRefresh : markerLayersForRefresh) {
            final PopulateControlledItemizedLayer markerLayer = getMarkerLayer(markerZLevelToRefresh, false);
            if (markerLayer == null) {
                continue;
            }
            markerLayer.populate();
            markerLayer.update();
        }
        markerLayersForRefresh.clear();

        //make sure map is redrawn. See e.g. #14787
        map.updateMap(true);
        return "l:" + layersSize + ",s:" + markerSymbolCache.size();
    }
mimics {@link #removeItem(MarkerInterface)} but w/o calling 'populate'
main/src/main/java/cgeo/geocaching/unifiedmap/geoitemlayer/MapsforgeVtmGeoItemLayer.java