Session session = entityManager.unwrap(Session.class);
session.doWork(connection -> {
    try (StatelessSession statelessSession = session.getSessionFactory().openStatelessSession(connection)) {
        // do stuff with stateless session
        // workaround for https://hibernate.atlassian.net/browse/HHH-4042
        ((SharedSessionContractImplementor) statelessSession).getJdbcCoordinator().executeBatch();
    }
});