Let's follow up this discussion at the Neptune Community
(this forum will be kept in read-only mode)
Is there any example how to make a filter on tree?
With SP01 released last week, it's now possible.
Please use element "TreeModel" with "NODE_ID" as key field and "PARENT_ID" as parent field and element "TreeNode" as child of TreeModel with properties bounded from the parent's model.
The code pattern "SAPUI5/List/Filter" can then be used just by replacing "items" by "nodes" and "yourList" by the name you have chosen for your TreeModel element.