@Override
        public void handle(Pong pong) {
            log.fine(() -> "Got pong from " + node + ": " + pong);
            if (pong.badResponse()) {
                clusterMonitor.failed(node, pong.error().get());
            } else {
                if (pong.activeDocuments().isPresent()) {
                    node.setActiveDocuments(pong.activeDocuments().get());
                    node.setTargetActiveDocuments(pong.targetActiveDocuments().get());
                }
                clusterMonitor.responded(node);
            }
        }
Calculate whether a subset of nodes in a group has enough coverage
container-search/src/main/java/com/yahoo/search/dispatch/searchcluster/SearchCluster.java