Generic observer handle returned by various observation APIs. The observation
remains active until the stop() method is called explicitly or the
observer instance is garbage collected. Therefore, to keep the observation
alive, you have to keep a reference to the corresponding observer.
Generic observer handle returned by various observation APIs. The observation remains active until the stop() method is called explicitly or the observer instance is garbage collected. Therefore, to keep the observation alive, you have to keep a reference to the corresponding observer.