docs: @Pure
  	public final void toPath2D(Path2d path) {
  		// loop on parts and build the path to draw
  		boolean firstPoint;
  		for (final PointGroup grp : groups()) {
  			firstPoint = true;
  			for (final Point2d pts : grp) {
  				final double x = pts.getX();
  				final double y = pts.getY();
  				if (firstPoint) {
  					path.moveTo(x, y);
  					firstPoint = false;
  				} else {
  					path.lineTo(x, y);
  				}
  			}
  		}
  	}