private static void addNodeVectorEntries(Map<String, Node> ret, String name, NodeVector<?> vector) {
        for (int j = 0; j < vector.length(); j++)
            ret.put(name + "[" + j + "]", (Node) vector.get(j));
    }
Returns a flat map of this node's direct children, including all NodeVectors' elements.
Keys are the node name, including index for vector elements, e.g. 'arr[0]'.
config-lib/src/main/java/com/yahoo/config/InnerNode.java