@Override
    public T_TREE_NODE getParent(final T_TREE_NODE node) {
        return parents.get(node);
    }
Creates a new instance with a given node as the root

@param root the node to be used as the root.
stroom-core-client-widget/src/main/java/stroom/widget/htree/client/treelayout/util/DefaultTreeForTreeLayout.java