public Builder buildUpon() {
        return builder().setBitmapProvider(bitmapProvider).setXAnchor(xAnchor).setYAnchor(yAnchor).setRotation(rotation).setFlat(flat);
    }
if the marker should rotate together with the map (flat mode) or should be displayed as billboard popup. Default is billboard.
main/src/main/java/cgeo/geocaching/models/geoitem/GeoIcon.java