JAXB cannot handle a nested java.util.Map correctly: Map<K, List> listValuedMap, or Map<K, Set> setValuedMap. To solve such problem, you have 2 choices:
- workaround - introduce a intermediate class to hold the nested List or Set.
- adapter - introduce a customized adapter.
GenericMapAdapter, GenericListValuedMapAdapter and GenericSetValuedAdapter are adapters for you to referrence.