clearAllBut() not working when expanded is true

[fadoers]

First of all, thank you for providing such an excellent project. When I expand all the items and then call the clearAllBut method, all top-level expandableItems will not be removed. This is the error message:

This is the code location:

Here is the use of the collapse method for each traversal, and the method will remove all subItems internally, and finally the value of itemCount will be greater than getItemCount()

This is the case: