Mmmh,
you are right, @ElementCollection is a EJB3.1 annotation (ähm a JPA2.0 which is part of EJB3.1).
ATM I have this options:
- store as a BLOB (MAP and its elements must be serializable)
- write your own mapper to store (and respect the EJB3.1 structure to port later :) )
- use a table with relation to store it