Hi!
I've been tracking all the method annoted by @TransactionAttribute and commented them until I find the only that caused the problem.
I finally found out the cause was the following method :
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public Long[] getStats(long mId, long eId) {
...
}
I changed the definition to :
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public List<Long> getStats(long mId, long eId)
And now it works :)