I am having following piece of code for saving the object in the database,

import java.util.HashMap;
import java.util.Map;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import org.hibernate.Session;
import org.hibernate.Transaction;
import model.Hibernatetest;
public class Test 
{
   static EntityManagerFactory objEntityManagerFactory;
   static Session objSession;
   static Transaction objTransaction;
   public static void main(String[] args) 
   {
        objSession = (Session) 
        objEntityManagerFactory.createEntityManager().getDelegate();
        //objTransaction = objSession.getTransaction();
        //objTransaction.begin();
        Hibernatetest obj = new Hibernatetest();
        obj.setName("Nobal");
        obj.setAddress("wlfjegtjwdfhdg");
        objSession.save(obj);
        obj.setName("235611111");
        objSession.flush();
       //objTransaction.commit();
        objSession.close();
    }

    public static void getConnection()
    {
        Map<String,String> properties = new HashMap<String,String>();
            properties.put("hibernate.connection.username", "root");
            properties.put("hibernate.connection.password", "root");
            properties.put("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
            properties.put("hibernate.connection.url", "jdbc:mysql://localhost:3306/hibernatetest");
            properties.put("hibernate.dialect", "org.hibernate.dialect.MySQLDialect");

         objEntityManagerFactory = Persistence.createEntityManagerFactory("Hibereg", properties);
    }
}

and the Persistence file is as follows:

<persistence xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/persistence" version="2.0">
<persistence-unit name="Hibereg">
<class>entities.Hibernatetest</class>
</persistence-unit>
</persistence>

Case 1:

The problem is when I run the above code using the hibernate-core-5.2.8.jar, and don't create any transaction object(you can see I commented the code related to transaction) then the above code gives me following exception.

'TransactionRequiredException' no transaction is in progress.'

However if I uncomment the code for the transaction, everything works well.

Case 2:

But when I run the code using hibernate-core-4.1.4.jar, by commenting the code for the transaction in code snippet provided above, It gives no such exception. That is , it never complains for the absence of transaction object and saves the object in the database.. What is going on in here?

I read over internet that transaction object is must for performing inserts and updates, (I am not sure about selects) but how the second scenario is executing successfully?