public NodeList state(Node.State first, Node.State... rest) {
        if (rest.length == 0) {
            return matching(node -> node.state() == first);
        }
        return state(EnumSet.of(first, rest));
    }
Returns the subset of nodes that are in any of the given state(s)
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/NodeList.java