Tree: Collapsing from ROOT problem

Hello,

Something weird is happening and I can’t understand.
I have a tree. I use an AbstractHierarchicalDataProvider for painting the TREE (I attach it).
This is the tree with the nodes expanded:

https://github.com/igux28/images/blob/master/all_expanded.PNG

When I collapse root parent (that contains leafs and items with children), only leafs are collaped, not all the opened items.

https://github.com/igux28/images/blob/master/after_collapsing_parent.PNG

As you can see, only the nodes that are directly referenced by the root are collapse. The ones under a node with leafs are still visible.

How can I do for collapsing all the node’s children (leafs and items)??
17643945.java (3.48 KB)

I have committed a project to github that reproduces the problem.

https://github.com/igux28/vaadin-tree-test

I would really appreciate your help !!