public double getCapacity() {
        double capacity = 0;
        for (StorageNode node : nodes) {
            capacity += node.getCapacity();
        }
        for (StorageGroup group : subgroups) {
            capacity += group.getCapacity();
        }
        return capacity;
    }
Returns all the nodes below this group
config-model/src/main/java/com/yahoo/vespa/model/content/StorageGroup.java