@Entity
@Table(name="user")
public class User {
   @Id
   @GeneratedValue(strategy=GenerationType.AUTO)
   private Integer id;
...
   @NotNull
   @NaturalId
   @Pattern(regexp = "[a-z\\d]+", message = "invalid.login.nickname")
   private String name;
...
}

SEVERE: Servlet.service() for servlet springServlet threw exception
java.lang.NullPointerException
   at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768)
   at org.hibernate.engine.internal.NaturalIdXrefDelegate$NaturalIdResolutionCache.cache(NaturalIdXrefDelegate.java:454)
   at org.hibernate.engine.internal.NaturalIdXrefDelegate.cacheNaturalIdCrossReference(NaturalIdXrefDelegate.java:92)
   at org.hibernate.engine.internal.StatefulPersistenceContext$1.manageLocalNaturalIdCrossReference(StatefulPersistenceContext.java:1769)
   at org.hibernate.action.internal.AbstractEntityInsertAction.handleNaturalIdPreSaveNotifications(AbstractEntityInsertAction.java:184)
   at org.hibernate.action.internal.AbstractEntityInsertAction.<init>(AbstractEntityInsertAction.java:75)
   at org.hibernate.action.internal.EntityIdentityInsertAction.<init>(EntityIdentityInsertAction.java:55)
   at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:317)
   at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:287)
   at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193)
   at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:126)
   at org.hibernate.ejb.event.EJB3PersistEventListener.saveWithGeneratedId(EJB3PersistEventListener.java:78)
   at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:208)
   at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:151)
   at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:78)
   at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:811)
   at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:786)
   at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:790)
   at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:859)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:365)
   at $Proxy52.persist(Unknown Source)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:240)
   at $Proxy52.persist(Unknown Source)
...

cfg.setProperty(DIALECT, "org.hibernate.dialect.MySQL5InnoDBDialect")
     .setProperty(HBM2DDL_AUTO, "update")
     .setProperty(USE_SECOND_LEVEL_CACHE, "false")
     .setProperty(ISOLATION, "2")

class Company {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    var id : Long = _

    @Version
    @Column(name = "version")
    var version : Int = _

    @NaturalId(mutable = true)
    var shortCode: String = _
    @Column(unique = true, nullable = false)
    var name:String = _
}