Hibernate - Unable to locate entity descriptor

I am new to Java (and Hibernate) and for learning Java I want to create plain Java app with simple CRUD operations using database. I found article with setting up hibernate so I followed it and the result is below:

import jakarta.persistence.*;
@Entity
@Table(name = "student")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private int id;

    @Column(name = "name")
    private String firstname;

    @Column(name = "lastname")
    private String lastname;

    // constructor
    // getters and setters

}

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "https://hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
        <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/db_student</property>
        <property name="hibernate.connection.username">my username</property>
        <property name="hibernate.connection.password">my password</property>

        <property name="hibernate.connection.pool_size">1</property>

        <property name="hibernate.current_session_context_class">thread</property>

        <mapping class="com.model.Student"/>
    </session-factory>
</hibernate-configuration>

HibernateUtil.java

public class HibernateUtil {

    private static SessionFactory sessionFactory;

    private static SessionFactory sessionJavaConfigFactory;

    private static SessionFactory buildSessionFactory() {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            Configuration configuration = new Configuration();
            configuration.configure("hibernate.cfg.xml");
            System.out.println("Hibernate Annotation Configuration loaded");

            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
            System.out.println("Hibernate Annotation serviceRegistry created");

            SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);

            return sessionFactory;
        }
        catch (Throwable ex) {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    private static SessionFactory buildSessionJavaConfigFactory() {
        try {
            Configuration configuration = new Configuration();

            //Create Properties, can be read from property files too
            Properties props = new Properties();
            props.put("hibernate.connection.driver_class", "org.postgresql.Driver");
            props.put("hibernate.connection.url", "jdbc:postgresql://localhost:5432/db_student");
            props.put("hibernate.connection.username", "my username");
            props.put("hibernate.connection.password", "my password");
            props.put("hibernate.current_session_context_class", "thread");

            configuration.setProperties(props);

            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
            System.out.println("Hibernate Java Config serviceRegistry created");

            SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);

            return sessionFactory;
        }
        catch (Throwable ex) {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        if(sessionFactory == null) sessionFactory = buildSessionFactory();
        return sessionFactory;
    }

    public static SessionFactory getSessionJavaConfigFactory() {
        if(sessionJavaConfigFactory == null) sessionJavaConfigFactory =   buildSessionJavaConfigFactory();
        return sessionJavaConfigFactory;
    }
}

And in Main.java I put:

public class Main {
    public static void main(String[] args) {
        Session session = HibernateUtil.getSessionFactory().openSession();
        Transaction transaction = session.beginTransaction();
        
        Student fetchedStudent = session.get(Student.class, 1);
        if (fetchedStudent != null) {
            System.out.println("Student found: " + fetchedStudent.getFirstname());
        } else {
            System.out.println("Student not found.");
        }
        transaction.commit();
        session.close();
    }
}

But I am constantly getting error:
Exception in thread "main" org.hibernate.UnknownEntityTypeException: Unable to locate entity descriptor: com.model.Student

I found that the problem can be with using older hibernate version, but in my case in my pom.xml I have:

 <dependency>
        <groupId>org.hibernate.orm</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>6.6.1.Final</version>
    </dependency>

This is because Hibernate doesn't know about your Student entity.

Since Hibernate 5 the Configuration.configure() method is broken. If you want to add mapping via hibernate.cfg.xml, use MetadataSources:

StandardServiceRegistry registry = new StandardServiceRegistryBuilder().configure().build();
SessionFactory sessionFactory = new MetadataSources(registry).buildMetadata().buildSessionFactory();

Or you can simply register your entity with Configuration.addAnnotatedClass()

configuration.addAnnotatedClass(Student.class);