Hibernate XML Mapping Exception

I'm trying to test the hibernate configuration of a project, but when I try to run the test it throws a MappinException saying that it does not known my entity, I checked the database and it is not creating the tables either, so my guess is that it is not reading the mapping files, but I checked that and the path is correct. And the package and class properties inside the mapping files is also correct (supposely).

Most of the questions I read are Annotation Focused, does anyone has an idea what's happening under the hood?

Thanks in advance

I have the following directory structure:

The hibernate.cfg.xml file it's like follows:

<hibernate-configuration>
    <session-factory>

        <!-- Hibernate Configuration -->
        <property name="hibernate.dialect">
            org.hibernate.dialect.MySQLDialect
        </property>
        <property name="hibernate.connection.driver_class">
            com.mysql.jdbc.Driver
        </property>
        <property name="hibernate.hbm2ddl.auto">
            update
        </property>

        <!-- Database Configuration -->
        <property name="hibernate.connection.url">
            jdbc:mysql://127.0.0.1:3306/library_management?createDatabaseIfNotExist=true
        </property>
        <property name="hibernate.connection.username">
            root
        </property>
        <property name="hibernate.connection.password">
            cetys
        </property>

        <!-- Class Mapping Files -->
        <mapping resource="Hibernate.config/mapping/Book.hbm.xml"/>
        <mapping resource="Hibernate.config/mapping/Classification.hbm.xml"/>
        <mapping resource="Hibernate.config/mapping/Collection.hbm.xml"/>
        <mapping resource="Hibernate.config/mapping/Loan.hbm.xml"/>
        <mapping resource="Hibernate.config/mapping/NonExistentRegistry.hbm.xml"/>

    </session-factory>
</hibernate-configuration>

The Loan mapping file is:

<hibernate-mapping package="com.cetys.cetyslibraryinventory.Core.DomainModels">
    <class name="Loan" table="loan">
        <meta attribute="class-description">
            This class contains the basic information for a Loan
        </meta>
        <id name="id" column="loan_id" type="int"></id>
        <many-to-one name="bookId" class="Book" unique="true"
                     column="book_id" cascade="all"/>  
    </class>
</hibernate-mapping>

The model:

package com.cetys.cetyslibraryinventory.Core.DomainModels;

//imports ommited

public class Loan implements Catalogable {

    private int id;

    private int book_id;

    protected Loan () {

    }

    public Loan ( int id, int book_id ) {
        this.id = id;
        this.book_id = book_id;
    }

    // Getters and Setters Ommited
}

And when I try to run the following:

     public class Program {

        public static void main ( String[] args ) {
            SessionFactory sessionFactory = null;

            Session session = null;

            Transaction tx = null;

            try {
                Configuration configuration = new Configuration();

                configuration.configure( "hibernate.cfg.xml" );

                ServiceRegistry serviceRegistry
                        = new StandardServiceRegistryBuilder().applySettings(
                                configuration.getProperties() ).build();
            sessionFactory = configuration.
                    buildSessionFactory( serviceRegistry );
            session = sessionFactory.openSession();

            Loan ln = new Loan( 0, 0 );

            tx = session.beginTransaction();
            session.save( ln );

            tx.commit();
        } catch ( Exception e ) {
            LOGGER.log( Level.SEVERE, e.getMessage(), e );
        } finally {
            if ( session != null ) {
                session.close();
            }
            if ( sessionFactory != null ) {
                sessionFactory.close();
            }
        }
    }

}

Exception Error:

SEVERE: Unknown entity: com.cetys.cetyslibraryinventory.Core.DomainModels.Loan
org.hibernate.MappingException: Unknown entity: com.cetys.cetyslibraryinventory.Core.DomainModels.Loan
    at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:776)
    at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1533)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:104)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
    at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
    at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
    at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:682)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:674)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:669)
    at com.cetys.cetyslibraryinventory.Program.main(Program.java:74)

Jun 08, 2016 10:04:41 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop
INFO: HHH10001008: Cleaning up connection pool [jdbc:mysql://127.0.0.1:3306/library_management?createDatabaseIfNotExist=true]