Model map with enum as a key

[Zbynek Vavros]

I got this class that has map with enums as keys:

public class MasterClass {

    private Map<MyEnum, String> config = Maps.newHashMap();
}

enum is classic:

public enum MyEnum {
    VALUE1,
    VALUE2
}

now I would like to use one entry of this map as a model for TextField:

new RequiredTextField<>("componentId", new
PropertyModel<>(modelObject.getConfig(), "VALUE1")))

but when saved to DB Hibernate says the key is String and Enum is expected:
java.lang.ClassCastException: java.lang.String cannot be cast to
java.lang.Enum

Using ChainingModel or
Model.of(modelObject.getConfig().get(MyEnum.VALUE1))) causes the value not
to be bind at all.

I know I can use "side" property and fill this map manually in onSubmit
just before saving to DB but would like to avoid that.

Thanks