I wrote a custom converter to map a list of custom type (List<MyBean>) to a s:checkboxlist tag. When I submit the form the convertFromString() method is called, so I have the list correctly populated with the selected values.
The problem is that it doesn't work the other way: when I try to pre-populate the form from the values in the list, the tag is always empty, because the convertToString() method is never called. Same happens for s:select with multiple="true".
I think it is a bug because if I change the tag to s:textfield, mapped to the same list, convertToString() is called and text box is populated.