@Override
    public boolean equals(Object other) {
        if (other == this) return true;
        if ( ! (other instanceof Cluster)) return false;
        return ((Cluster)other).id().equals(this.id);
    }
Add or update (based on "at" time) a scaling event
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/applications/Cluster.java