Connection retorna null

Ola, Estou tentando passar as informações do meu EntityManager para um Connection e sempre me retorna null

`
@PersistenceContext(unitName = UNIT_NAME)
private EntityManager entityManager;

public void teste(){
Connection connection = entityManager.unwrap(java.sql.Connection.class);
}
`

teria alguma forma de resolver?

Persistence

<persistence-unit name="autenticacaoPU" transaction-type="JTA">
    <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
    <jta-data-source>jdbc/gestao</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
        <property name="hibernate.transaction.jta.platform" value="org.hibernate.service.jta.platform.internal.SunOneJtaPlatform"/>
        <property name="hibernate.show_sql" value="true"/>
        <property name="hibernate.format_sql" value="true"/>
        <property name="hibernate.use_sql_comments" value="false"/>
        <property name="hibernate.jdbc.wrap_result_sets" value="false"/>
        <property name="hibernate.hibernate.cache.use_query_cache" value="true"/>
        <property name="hibernate.hbm2ddl.auto" value="validate"/>
    </properties>
</persistence-unit>