Dynamic Forms Angular 2 - Checkbox

I am new in Angular 2. I am trying to expand dynamic forms according to http://ift.tt/2sPAe7i. I did input radios and work as I need. But now I am trying to do checkboxes, but there is a problem. I have a group of checkboxes and I get only boolean value, if some checkbox is checked. Bud I need values, which checkboxes is checked. There is my plunker: http://ift.tt/2sl3zmM

Thanks for help!