Stroke stroke = sf.stroke(ff.literal("#000000"), null, null, null, null, null, null);
Fill fill = sf.fill(null, ff.literal(Color.BLUE), ff.literal(1.0));
// OnLineResource implemented by gt-metadata - so no factory!
OnLineResourceImpl svg = new OnLineResourceImpl(new URI("file:city.svg"));
svg.freeze(); // freeze to prevent modification at runtime
OnLineResourceImpl png = new OnLineResourceImpl(new URI("file:city.png"));
png.freeze(); // freeze to prevent modification at runtime
//