Hibernate Configuration using Java Singleton Class

package com.mysite.firstJavaDbApp.config;
import java.util.Properties;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import com.mysite.firstJavaDbApp.beans.Employee;
import com.mysite.firstJavaDbApp.beans.Student;
public class HibernateDbConfig {
private SessionFactory sessionFactory;
private static HibernateDbConfig hibernateDbConfig;
private HibernateDbConfig() {
 Properties properties = new Properties();
 properties.put("hibernate.connection.username", "shyam");
 properties.put("hibernate.connection.password", "Pass@123");
 properties.put("hibernate.connection.driver_class", "com.mysql.cj.jdbc.Driver");
 properties.put("hibernate.connection.url", "jdbc:mysql://localhost:3306/javaee");
 properties.put("hibernate.connection.hbm2ddl.auto", "update");
 properties.put("hibernate.dialect", "org.hibernate.dialect.MySQLDialect");
 properties.put("hibernate.connection.show_sql", "true");
 Configuration configuration = new Configuration();
 configuration.setProperties(properties);
 configuration.addAnnotatedClass(Employee.class)
   .addAnnotatedClass(Student.class);
 ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
   .applySettings(configuration.getProperties()).build();
 sessionFactory = configuration.buildSessionFactory();
}
public static HibernateDbConfig getInstance() {
 hibernateDbConfig = (hibernateDbConfig == null) ? new HibernateDbConfig() : hibernateDbConfig;
 return hibernateDbConfig;
}
public SessionFactory getSessionFactory() {
 return sessionFactory;
}
}