The Search of cascading DropDownLists is not working with wrappers

[eyupyusein]

The following dojo demonstrates how the searching should behave:
https://dojo.telerik.com/NvwCiymq/3

The same should happen with the wrappers:
https://netcorerepl.telerik.com/GzOqvhkq024jFx6s55

It should display only Konbu:

I suppose the issue is related to the fact that the Core/MVC counterpart requires additional value to be sent manually, which I think should happen automatically with internal code:

    function filterProducts() {
        return {
            categories: $("#categories").val()
        };
    }