ObjectMapper should detect if the session is already opened

[VadimKirilchuk]

Please refer to stackoverflow

When spring integration test is annotated with @transactional, persists a child entity and then calls a controller to return the parent entity then exception is thrown. It happens because the child entity is stored in a first session opened by @transactional and object mapper tries to open another session to convert the parent entity to json, so the child entity appears in two sessions which lead to the exception.

[cowtowncoder]

Sounds like transaction could be stored in a context attribute (SerializerProvider.setAttribute() etc) when being created, then accessed from there.
Pull Requests would be most welcome!