The main goal of this sample is to show a HandlerInterceptor which works similarly to Hibernate's OpenSessionInViewInterceptor.
ExposedTransactionPerRequestInterceptor creates a transaction per request and rollbacks it if an exception occurred.
This is useful only if you're exposing your DAO-entities out of the service layer, since Exposed requires a transaction in the context when accessing any entity's fields. In the other cases @Transactional service methods are more suitable.