public static ArrayList<BitmapTileLayer> getBitmapTileLayersVTM(final Context context, final Map map) {
        final ArrayList<BitmapTileLayer> result = new ArrayList<>();
        final File[] files = getMBTilesSources(context);
        if (files != null) {
            for (File file : files) {
                result.add(new BitmapTileLayer(map, new MBTilesBitmapTileSource(file.getAbsolutePath(), 192, null)));
            }
        }
        return result;
    }
returns a list of BitmapTileLayers for all .mbtiles used for background maps (VTM variant)
main/src/main/java/cgeo/geocaching/unifiedmap/layers/MBTilesLayerHelper.java