AASX Serialization of derived model element fails

[tobijk2]

When serializing aas model elements (derived from the Default* implementation) an exception is encountered:
com.fasterxml.jackson.databind.JsonMappingException: local part cannot be "null" when creating a QName (through reference chain: model.Submodel["description"])
As the derived model elements do not implement new properties, just provide some additional helper, this is not an expected behavior.
Attached is a minimal test project to trigger the exception:
aasxSerializationTest.zip