code: public void stop(final GeometryFunction callback) throws GeometryMergeException {
  		if (!busy) {
  			throw new GeometryMergeException("Can't stop the merging process since it is not activated.");
  		}
  		if (callback == null) {
  			cancel();
  			return;
  		}
  		merge(new GeometryFunction() {
  
  			public void execute(Geometry geometry) {
  				callback.execute(geometry);
  				try {
  					clearGeometries();
  				} catch (GeometryMergeException e) {
  				}
  				busy = false;
  				eventBus.fireEvent(new GeometryMergeStopEvent(geometry));
  			}
  		});
  	}
docs: End the merging process by effectively executing the merge operation and returning the result through a
  call-back.
  
  @param callback The call-back function that will receive the merged geometry.
  @throws GeometryMergeException Thrown in case the merging process has not been started or some other merging
  error.