@Override
    protected double maintain() {
        for (var nodeType : NodeType.values()) {
            if (!nodeType.isHost()) continue;
            boolean resume = canUpgradeOsOf(nodeType);
            nodeRepository().osVersions().resumeUpgradeOf(nodeType, resume);
        }
        return 1.0;
    }
This maintainer (de)activates OS upgrades according to Vespa upgrade status of nodes in this repository.

If a node is upgrading to a new Vespa version, any ongoing OS upgrade will be paused for all nodes of that type. OS
upgrades will resume once all nodes of that type have completed their Vespa upgrade.

@author mpolden
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/OsUpgradeActivator.java