public NodeList nodeType(NodeType first, NodeType... rest) {
        if (rest.length == 0) {
            return matching(node -> node.type() == first);
        }
        EnumSet<NodeType> nodeTypes = EnumSet.of(first, rest);
        return matching(node -> nodeTypes.contains(node.type()));
    }
Returns the subset of nodes matching any of the given node type(s)
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/NodeList.java