为什么我的hibernate元模型 获取类的字段为空呢

i use hibernate-jpamodelgen-1.2.0.Final.jar tool in javaee6 Environment  to produce Meta Model class.

but  when i test
   */
    public static void main(String[] args) {
     System.out.println(Models_.modelName);
    } why i  get  null?

myrun Environment   is
hibernate-commons-annotations-4.0.2.Final.jar
hibernate-core-4.3.0.Beta3.jar
hibernate-entitymanager-4.3.0.Beta3.jar
hibernate-jpa-2.1-api-1.0.0.Draft-16.jar

can any help me ? thanks very much


@Entity
@Table(name = "et_models")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Models.findAll", query = "SELECT m FROM Models m"),
    @NamedQuery(name = "Models.findByModelName", query = "SELECT m FROM Models m WHERE m.modelName = :modelName"),
    @NamedQuery(name = "Models.findByModelDesc", query = "SELECT m FROM Models m WHERE m.modelDesc = :modelDesc"),
    @NamedQuery(name = "Models.findByServerCodeBase", query = "SELECT m FROM Models m WHERE m.serverCodeBase = :serverCodeBase"),
    @NamedQuery(name = "Models.findByClientCodeBase", query = "SELECT m FROM Models m WHERE m.clientCodeBase = :clientCodeBase"),
    @NamedQuery(name = "Models.findByLoaderCodeBase", query = "SELECT m FROM Models m WHERE m.loaderCodeBase = :loaderCodeBase"),
    @NamedQuery(name = "Models.findByImporterCodeBase", query = "SELECT m FROM Models m WHERE m.importerCodeBase = :importerCodeBase"),
    @NamedQuery(name = "Models.findByCacheCodeBase", query = "SELECT m FROM Models m WHERE m.cacheCodeBase = :cacheCodeBase"),
    @NamedQuery(name = "Models.findByCreatedBy", query = "SELECT m FROM Models m WHERE m.createdBy = :createdBy"),
    @NamedQuery(name = "Models.findByCreationDate", query = "SELECT m FROM Models m WHERE m.creationDate = :creationDate"),
    @NamedQuery(name = "Models.findByLastUpdatedBy", query = "SELECT m FROM Models m WHERE m.lastUpdatedBy = :lastUpdatedBy"),
    @NamedQuery(name = "Models.findByLastUpdateDate", query = "SELECT m FROM Models m WHERE m.lastUpdateDate = :lastUpdateDate"),
    @NamedQuery(name = "Models.findByLastUpdateLogin", query = "SELECT m FROM Models m WHERE m.lastUpdateLogin = :lastUpdateLogin")})
public class Models implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @Column(name = "model_name")
    private String modelName;
    @Basic(optional = false)
    @Column(name = "model_desc")
    private String modelDesc;
    @Column(name = "server_code_base")
    private String serverCodeBase;
    @Column(name = "client_code_base")
    private String clientCodeBase;
    @Column(name = "loader_code_base")
    private String loaderCodeBase;
    @Column(name = "importer_code_base")
    private String importerCodeBase;
    @Column(name = "cache_code_base")
    private String cacheCodeBase;
    @Basic(optional = false)
    @Column(name = "created_by")
    private long createdBy;
    @Basic(optional = false)
    @Column(name = "creation_date")
    @Temporal(TemporalType.TIMESTAMP)
    private Date creationDate;
    @Basic(optional = false)
    @Column(name = "last_updated_by")
    private long lastUpdatedBy;
    @Basic(optional = false)
    @Column(name = "last_update_date")
    @Temporal(TemporalType.TIMESTAMP)
    private Date lastUpdateDate;
    @Basic(optional = false)
    @Column(name = "last_update_login")
    private long lastUpdateLogin;
    @OneToMany(mappedBy = "modelName")
  // @XmlElement(name="codingSchemesList")
    private List<CodingSchemes> codingSchemesList;


    public Models() {
    }


    public Models(String modelName) {
        this.modelName = modelName;
    }


    public Models(String modelName, String modelDesc, long createdBy, Date creationDate, long lastUpdatedBy, Date lastUpdateDate, long lastUpdateLogin) {
        this.modelName = modelName;
        this.modelDesc = modelDesc;
        this.createdBy = createdBy;
        this.creationDate = creationDate;
        this.lastUpdatedBy = lastUpdatedBy;
        this.lastUpdateDate = lastUpdateDate;
        this.lastUpdateLogin = lastUpdateLogin;
    }
.............................................
@Generated(value = "org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor")
@StaticMetamodel(Models.class)
public abstract class Models_ {


          public static volatile SingularAttribute<Models, Date> creationDate;
          public static volatile ListAttribute<Models, CodingSchemes> codingSchemesList;
          public static volatile SingularAttribute<Models, String> modelName;
          public static volatile SingularAttribute<Models, Long> createdBy;
          public static volatile SingularAttribute<Models, String> importerCodeBase;
          public static volatile SingularAttribute<Models, Long> lastUpdateLogin;
          public static volatile SingularAttribute<Models, Long> lastUpdatedBy;
          public static volatile SingularAttribute<Models, String> modelDesc;
          public static volatile SingularAttribute<Models, String> loaderCodeBase;
          public static volatile SingularAttribute<Models, String> cacheCodeBase;
          public static volatile SingularAttribute<Models, String> serverCodeBase;
          public static volatile SingularAttribute<Models, String> clientCodeBase;
          public static volatile SingularAttribute<Models, Date> lastUpdateDate;


}