[Combobox] Filtering fails to show Option Group Labels

[derekrjones]

Describe the bug
when applying a filter to combobox the Option Group Labels sometimes fail to show

To Reproduce
Steps to reproduce the behavior:

1. Go to option groups example in the documentation for the combobox
2. Click on the combobox and type 'b'
3. group labels appear correctly
4. type 'e' ('be')
5. 'Fruits' group label does not appear
6. delete last character (so just 'b')
7. 'Fruits' group label does not appear

Screenshots

[derekrjones]

related: #272 . Looks like the previous fix wasn't quite correct.

[banolist]

I think the problem is with defining id in createListState, option group don't have id. when the list is updated, "Key" from listbox skips rendering because of duplicate empty keys