void updateForDistributor(int distributorIndex, ContentClusterStats clusterStats) {
        if (!distributors.contains(distributorIndex)) {
            return;
        }
        nonUpdatedDistributors.remove(distributorIndex);
        addStatsFromDistributor(distributorIndex, clusterStats);
    }
Update the aggregator with the newest available stats from a distributor.
clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregator.java