void aggregateNodeStats(StorageGroup group) {
                for (StorageNode n : group.getNodes()) {
                    nodeCount++;
                    highestNodeDistributionKey = Math.max(highestNodeDistributionKey, n.getDistributionKey());
                }
                for (StorageGroup g : group.getSubgroups()) {
                    aggregateNodeStats(g);
                }
            }
Returns of memory reserved on a host. Memory is reserved for the jvm if the cluster is combined
config-model/src/main/java/com/yahoo/vespa/model/content/cluster/ContentCluster.java