Caused by: javax.ejb.EJBException: java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: User is not mapped [SELECT u FROM User as u WHERE u.name = :name]

@Entity
@Table(name = "PL1_USER")
public class User implements Serializable {
...

@Stateless
public class UserService {

@PersistenceContext(unitName = "my-unit")
private EntityManager entityManager;

public User getUser(String username) {
    TypedQuery<User> query = entityManager.createQuery("SELECT u FROM User as u WHERE u.name = :name", User.class);
    query.setParameter("name", username);
    return query.getSingleResult();
}
}

<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd" version="2.0">

<persistence-unit name="my-unit" transaction-type="JTA">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <jta-data-source>java:jboss/datasource/MY-DS</jta-data-source>

    <jar-file>Entity.jar</jar-file>

    <properties>
        <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.JBossTransactionManagerLookup" />
        <property name="hibernate.archive.autodetection" value="class, hbm" />
        <property name="hibernate.show_sql" value="false" />
        <property name="hibernate.format_sql" value="true" />
        <property name="hibernate.use_sql_comments" value="false" />
        <property name="hibernate.jdbc.batch_size" value="30" />
        <property name="hibernate.jdbc.fetch_size" value="100" />
        <property name="hibernate.max_fetch_depth" value="0" />
        <property name="hibernate.order_updates" value="true" />
        <property name="hibernate.use_identifier_rollback" value="true" />

        <!-- JDBC Driver returns row count for batch statements -->
        <property name="hibernate.jdbc.batch_versioned_data" value="true" />

        <property name="hibernate.dialect" value="org.hibernate.dialect.DB2400Dialect" />

    </properties>
</persistence-unit>