@Override
            public synchronized void onGroupValuesChanged(final WatcherHolder holder,
                                             final GroupConfigTable.GroupConfigItems groupConfigItems) {
                notifyGroupValues((GroupConfigChangeWatcher) holder.getWatcher(), groupConfigItems);
            }
Implement Config Watcher register using client listening.
oap-server/server-configuration/configuration-api/src/main/java/org/apache/skywalking/oap/server/configuration/api/ListeningConfigWatcherRegister.java