How to get combobox multiselect's items in Vaadin 8.0.0

Hi,

I’m using Vaadin 8.0.0 and i don’t know how to get combobox multiselect’s items.
I tryed by passing by DataProvider but i didn’t find anything useful.

Please, can you help me and telle me how to do “getItems()” like in Vaadin 8.0.0 for a comboboxMultiselect ?