@Nullable
    @Override
    public Geopoint getCenter() {
        //shortcut for markers
        if (getPoints().size() == 1) {
            return getPoints().get(0);
        }
        final Viewport vp = getViewport();
        return vp == null ? null : vp.getCenter();
    }
This constructor is specifically for creating objects with applied default style
main/src/main/java/cgeo/geocaching/models/geoitem/GeoPrimitive.java