private static void parseService(Inspector service, Map<ClusterInfo, DeploymentMetricsAggregator> clusterMetricsMap) {
        String serviceName = service.field("name").asString();
        if (!WANTED_METRIC_SERVICES.contains(serviceName)) return;
        service.field("metrics").traverse((ArrayTraverser) (i, metric) ->
                addMetricsToAggregator(serviceName, metric, clusterMetricsMap)
        );
    }
Call the metrics API on each host and aggregate the metrics
into a single value, grouped by cluster.
configserver/src/main/java/com/yahoo/vespa/config/server/metrics/ClusterDeploymentMetricsRetriever.java