code: public Bbox getBounds() {
  		Bbox bounds = null;
  		if (!isEmpty()) {
  			for (Polygon polygon : polygons) {
  				if (bounds == null) {
  					bounds = polygon.getBounds();
  				} else {
  					bounds = bounds.union(polygon.getBounds());
  				}
  			}
  		}
  		return bounds;
  	}
docs: Return the closest bounding box around the geometry.