@Override
    protected double maintain() {
        NodeList expired = getExpiredNodes();

        if ( ! expired.isEmpty()) {
            log.info(this.getClass().getSimpleName() + " found " + expired.size() + " expired nodes: " + expired);
            expire(expired.asList());
        }

        metric.add("nodes.expired." + fromState, expired.size(), null);
        return 1.0;
    }
The event record type which contains the timestamp to use for expiry
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/Expirer.java