import javax.management.*;
import javax.management.openmbean.CompositeData;
import com.sun.management.GarbageCollectionNotificationInfo;
import com.sun.management.GcInfo;

static AutoCloseable onGCNotification(final VF1<GarbageCollectionNotificationInfo> theListener) {
  final NotificationListener listener = new NotificationListener {
    public void handleNotification(Notification notification, O handback) {
      // extract garbage collection information from notification.
      GarbageCollectionNotificationInfo gcInfo = GarbageCollectionNotificationInfo.from((CompositeData) notification.getUserData());
      pcallF(theListener, gcInfo);
    }
  };

  for (GarbageCollectorMXBean gcBean : ManagementFactory.getGarbageCollectorMXBeans())
    ((NotificationEmitter) gcBean).addNotificationListener(listener, null, null);
    
  ret autoCloseable {
    for (GarbageCollectorMXBean gcBean : ManagementFactory.getGarbageCollectorMXBeans())
      ((NotificationEmitter) gcBean).removeNotificationListener(listener, null, null);
  };
}