How to set a Tree checkbox to indeterminate state

[maxsanii2020]

In a Tree, I need to set a parent node to indeterminate state in the back-end, but I can't find a property for that. I can set a node to checked/unchecked by setting the @checked property in the back-end, but for indeterminate state, I can't find a way to do it.

I know there is a way to do it on the JS: $('#domID').checkbox().state('indeterminate');

but is there a way to do that on the back-end?