@Override
    public void disableUpgrade(NodeType type) {
        NodeList nodesUpgrading = nodeRepository.nodes().list()
                                                .nodeType(type)
                                                .changingOsVersion();
        if (nodesUpgrading.isEmpty()) return;
        LOG.info("Disabling OS upgrade of all " + type + " nodes");
        nodeRepository.nodes().upgradeOs(NodeListFilter.from(nodesUpgrading.asList()), Optional.empty());
    }
An upgrader that delegates the upgrade to the node itself, triggered by changing its wanted OS version. Downgrades
are not supported.

Used in clouds where nodes can upgrade themselves in-place, without data loss.

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