public Node highestIndex(NodeList nodes) {
        Node highestIndex = null;
        for (Node node : nodes) {
            if (highestIndex == null || node.allocation().get().membership().index() >
                                        highestIndex.allocation().get().membership().index())
                highestIndex = node;
        }
        return highestIndex;
    }
Returns the node with the highest membership index from the given set of allocated nodes
node-repository/src/test/java/com/yahoo/vespa/hosted/provision/maintenance/NodeFailTester.java