Spring web request interceptor that binds a JPA EntityManager to the
thread for the entire processing of the request. Intended for the "Open
EntityManager in View" pattern, i.e. to allow for lazy loading in
web views despite the original transactions already being completed.
This interceptor makes JPA EntityManagers available via the current thread,
which will be autodetected by transaction managers. It is suitable for service
layer transactions via JpaTransactionManager
or JtaTransactionManager as well
as for non-transactional read-only execution.
In contrast to OpenEntityManagerInViewFilter, this interceptor is set
up in a Spring application context and can thus take advantage of bean wiring.
Return the name of the request attribute that identifies that a request is
already filtered. Default implementation takes the toString representation
of the EntityManagerFactory instance and appends ".FILTERED".