Gets or sets if a new Session should be created when no transactional Session can be found for the current thread.
true if allowed to create non-transaction session; otherwise,
HibernateTemplate is aware of a corresponding Session bound to the current thread, for example when using HibernateTransactionManager. If allowCreate is true, a new non-transactional Session will be created if none found, which needs to be closed at the end of the operation. If false, an InvalidOperationException will get thrown in this case.