in src/main/java/org/apache/sling/discovery/impl/support/MetricReporter.java [276:286]
private void handleChanged(TopologyView oldView, TopologyView newView) {
changedEvents.incrementAndGet();
topologyIsUndefined.set(0);
updateLocalClusterInstances(oldView, newView);
updateLeaderSwitch(oldView, newView);
updateProperties(newView);
updateRemote(newView);
}