Converter for a collection / select fields

Hi,
Have data item that contains a Set.
I am trying to bind it to a customField that includes a ListSelect.
One of the fields in the pojo needs to be the displayed value in the ListSelect.
So I tried writng an myItemToString converter, but that doesn’t see to do the trick.
My Pojo here is called PermittedEntityToUserJson.
As fas as I can say I wrote it ok. But it never kicks in, I tried adding prints and I see it is never used.

[code]
public class PermittedEntityToUserJsonToStringConverter implements Converter<String, PermittedEntityToUserJson>{
private static final long serialVersionUID = 1L;

@Override
public PermittedEntityToUserJson convertToModel(String value,
        Class<? extends PermittedEntityToUserJson> targetType, Locale locale)
        throws com.vaadin.data.util.converter.Converter.ConversionException {
    PermittedEntityToUserJson json = new PermittedEntityToUserJson();
    json.setAddress(value.toString());
    if(value.contains("@")){
        
        json.setEntityType(EntityType.USER);            
    } else {
        json.setEntityType(EntityType.ACTIVE_DIRECTORY_GROUP);
    }
    System.out.println("In the converter!!!");
    return json;
}

@Override
public String convertToPresentation(PermittedEntityToUserJson value,
        Class<? extends String> targetType, Locale locale)
        throws com.vaadin.data.util.converter.Converter.ConversionException {
    return value.getAddress();
}

@Override
public Class<PermittedEntityToUserJson> getModelType() {
    return PermittedEntityToUserJson.class;
}

@Override
public Class<String> getPresentationType() {
    return String.class;
}

}
[/code]It then occured to me that maybe I needed to write the convertion from Set <=> Set.
But then I have an issue - I can’t return a Set class, because, well, this is java.
So I tired just using Sets and cast inside, but that didn’t kick in either.
What am I missing?
I hav a way of circumventing this, but this using a converter an data binding is so much more elegant, I’d like to use it in the rest of my project. All the converter example I found related to a single property, not collections of properties and selects.