Custom Map serialization/de-serialization

I came up with a problem related to serialization of Map having non-String key using Flex/Spring BlazeDS.

My class looks like about this:

Code:

---

MyEntity{
private Map<Entity2, Enum1> myMap
}

---

During serialization from Flex to Java they key value of myMap gets converted into String automatically and it gives exception in my service layer validations. I guess this automatic conversion from entity to string is done by BlazeDS, because it assumes, that all map keys must be string.

Is it possible to fix this behavior (key should stay as entity) using Spring BlazeDS features?