Combo Box: Multi Select with check boxes

Is there any version of polymer combo box which supports multiple selection with checkboxes? I have started working on it but wanted to confirm before going too far. Also you can suggest if there are any better routes to achieve this than customizing vaadin combo box component. Thanks.

Hello Jimmy,
We have a ticket in the <vaadin-combo-box> roadmap for multi-select feature. You can follow the discussion at https://github.com/vaadin/vaadin-combo-box/issues/88

Thanks for the response Tomi.
We actually need this in next 4 weeks and I guess the feature may not be available by then - so I will have to continue customizing the combo box.