java.lang.ClassCastException in ListMultipleChoice

[Agent Mahone]

Hi guys, I have a simple question.

I´m using a ListMultipleChoice in my form.
The selected items should be binded to "Car.color" as "List<Car> cars".

If I bind the ListMultipleChoice to "cars", I´ll get a 
java.lang.ClassCastException
because wicket trys to map a List<String> to List<Car>.

java.lang.ClassCastException: java.lang.String cannot be cast to com.***.***.Car

Any ideas???

Thanks for your help