@Override
        public boolean isAvailable() {
            boolean isValid = true;
            for (ImmutablePair<String, Uri> mapUri : mapUris) {
                isValid &= isValidMapFile(mapUri.right);
            }
            return isValid;
        }
Create new render layer, if mapfile exists
main/src/main/java/cgeo/geocaching/maps/mapsforge/MapsforgeMapProvider.java