code: <V> V execute(final TransactionalClosureWithReturn<V> closure) {
          return getSessionFactory().doInSession(
                  new Callable<V>() {
                      @Override
                      public V call() {
                          PersistenceSession persistenceSession = getPersistenceSession();
                          persistenceSession.getServicesInjector().injectServicesInto(closure);
                          return doExecute(closure);
                      }
                  }
          );
      }
docs: region > execute (Isis integration)