fixed some code

core-java-modules/core-java-8-2/src/main/java/com/baeldung/optionalReturnType/PersistOptionalTypeExample.java

@@ -12,6 +12,8 @@ public class PersistOptionalTypeExample {
 	
 	static EntityManager entityManager = emf.createEntityManager();
 	
+	//to run this app, uncomment the follow line in META-INF/persistence.xml
+	//<class>com.baeldung.optionalReturnType.UserOptionalField</class>
 	public static void main(String[] args) {
 		UserOptionalField user1 = new UserOptionalField();
 		user1.setUserId(1l);

core-java-modules/core-java-8-2/src/main/java/com/baeldung/optionalReturnType/PersistUserExample.java

@@ -4,7 +4,7 @@ import javax.persistence.EntityManager;
 import javax.persistence.EntityManagerFactory;
 import javax.persistence.Persistence;
 
-public class PersistUserNoOptionalExample {
+public class PersistUserExample {
 	static String persistenceUnit = "com.baeldung.optionalReturnType";
 	static EntityManagerFactory emf = Persistence.createEntityManagerFactory(persistenceUnit);
 	

core-java-modules/core-java-8-2/src/main/resources/META-INF/persistence.xml

@@ -9,9 +9,11 @@
 		transaction-type="RESOURCE_LOCAL">
 		<description>Persist Optional Return Type Demo</description>
 		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
-		<class>com.baeldung.optionalReturnType.UserNoOptional</class>
+		<class>com.baeldung.optionalReturnType.User</class>
 		<class>com.baeldung.optionalReturnType.UserOptional</class>
+		<!-- 
 		<class>com.baeldung.optionalReturnType.UserOptionalField</class>
+		-->
 		<exclude-unlisted-classes>true</exclude-unlisted-classes>
 
 		<properties>