<persistence ... version="2.0">
   <persistence-unit name="my-pu">
     <description>My Persistence Unit</description>
     <provider>org.hibernate.ejb.HibernatePersistence</provider>
     <mapping-file>META-INF/mappingFile.xml</mapping-file>
     <jar-file>packedEntity.jar</jar-file>
     <class>sample.Book</class>
	 ....
     <properties>
        <property name="javax.persistence.jdbc.driver" value="org.h2.Driver" />
        <property name="javax.persistence.jdbc.url"    value="jdbc:h2:mem:test" />
        <property name="javax.persistence.jdbc.user" value="sa" />
        <property name="javax.persistence.jdbc.password" value="123" />
        ...
        <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
        <property name="hibernate.hbm2ddl.auto" value="validate" />
        <property name="show_sql" value="true"/>
     </properties>
   </persistence-unit>
</persistence>

<?xml version="1.0" encoding="UTF-8"?>
<entity-mappings 
    xmlns="http://java.sun.com/xml/ns/persistence/orm"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm 
        http://java.sun.com/xml/ns/persistence/orm_2_0.xsd"
    version="2.0">
	<entity class="samples.Book"
            access="FIELD" name="Book">
        <attributes>
            <id name="id"/>
            <basic name="book_name"/>
            <basic name="author_id"/>
        </attributes>
    </entity>

</entity-mappings>

spring.datasource.url=jdbc:h2:file:./data/jokes
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.h2.console.enabled=true

spring.jpa.generate-ddl=true
spring.jpa.hibernate.ddl-auto=validate
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.H2Dialect

@Entity
@Table(name = "book")
public class Book {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "book_name")
    private String bookName;
    
    @ManyToOne
    @JoinColumn(name = "author_id")
    private Author author;

    @OneToMany(mappedBy = "book", fetch = FetchType.LAZY)
    private List<Page> pages;
    
}

Query query = entitymanager.createQuery("from Book");
List<Book> list=query.getResultList();