How to create multilevel treegrid

Hello Vaadin Team,
I’m using latest version of vaadin with springboot.
I want to implement hierarchical tree of 4 level I go through this example

and try to implement the same by using AbstractHierarchicalDataprovider ,I can able to create 2 level tree but like how can I implement the multilevel treegrid can anyone help me on it or share any code example for it

Implementing a 4-level tree shouldn’t be conceptually any different from a 2-level tree. You just need to implement the methods fetchChildrenFromBackEnd, getChildCount, and hasChildren. All three methods are based on a certain node, which can get from the input Query object. The count method returns the number of immediate child items. The fetch method returns the immediate child items based on offset and limit. The hasChildren returns true if the current node has children.