code: public void update(Bbox mapBounds) {
  		for (final SnappingRule condition : snappingRules) {
  			condition.getSourceProvider().update(mapBounds);
  			condition.getSourceProvider().getSnappingSources(new GeometryArrayFunction() {
  
  				public void execute(Geometry[] geometries) {
  					condition.getAlgorithm().setGeometries(geometries);
  				}
  			});
  		}
  	}
docs: Update the playing field for snapping, by providing a bounding box wherein the source providers should present
  their geometries.
  
  @param mapBounds The bounding box wherein we expect snapping to occur. Is usually the current view on the map.