This annotation is the equivalent to @Transactional without transactions.
Not using @UnitOfWork or @Transactional when accessing your database is
not recommended. If you do so you might end up with a lot of open connections.
The difference between @Transactional and @UnitOfWork is that @UnitOfWork
does not open or commit any transactions. This may be faster for simple reads.
But if you alter data you should use @Transactional.
You can use UnitOfWork simultaneously on many levels (methods, classes etc).
But only the most outer declaration will open a unit of work. There us no
nesting of unit of works taking place.
You can mix @UnitOfWork and @Transactional. UnitOfWork will keep the unit open,
and all levels annotated with @Transactional will open and commit transactions.