quick updates and cleanup

spring-hibernate4/src/main/java/org/baeldung/spring/PersistenceConfig.java

@@ -5,6 +5,7 @@ import java.util.Properties;
 import javax.sql.DataSource;
 
 import org.apache.tomcat.dbcp.dbcp.BasicDataSource;
+import org.hibernate.SessionFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan;
@@ -53,9 +54,10 @@ public class PersistenceConfig {
     }
 
     @Bean
-    public HibernateTransactionManager transactionManager() {
+    @Autowired
+    public HibernateTransactionManager transactionManager(final SessionFactory sessionFactory) {
         final HibernateTransactionManager txManager = new HibernateTransactionManager();
-        txManager.setSessionFactory(sessionFactory().getObject());
+        txManager.setSessionFactory(sessionFactory);
 
         return txManager;
     }