休眠生成器无法插入唯一标识符

    ...org.hibernate.exception.ConstraintViolationException: 
could not insert: [com.gorkwobbler.shadowrun.karma.domain.AttributeScore]
    ...java.sql.SQLException: 
Caused by: java.sql.SQLException: Cannot insert the value NULL into column 'id', table 'KARMA_DEV.dbo.Character'; column does not allow nulls. INSERT fails.

我可以看到正在发表以下插入声明:

Hibernate: insert into character (version, alias, firstName, lastName) values (?, ?, ?, ?)

目前,我的表模式很简单:

Character(
 id uniqueidentifier, --primary key
 alias varchar(max),
 firstName varchar(max),
 lastName varchar(max),
 version int --for hibernate
)

我使用的是SQLServer2008R2速成版。

我的注释在映射的超类DomainEntity和具体类KarmaCharacter之间拆分:

@MappedSuperclass
public abstract class DomainEntity implements Serializable /* Needed for HOM retainUnsaved */ {
    private static final long serialVersionUID = 1L;
    private String id;
    private Integer version;

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Generated(value=GenerationTime.INSERT)
    //@GeneratedValue(generator="hibernate-uuid.hex")
    //@GenericGenerator(name="hibernate-uuid.hex", strategy="org.hibernate.id.UUIDHexGenerator", parameters=@Parameter(name="separator", value="-"))
    @AccessType(value="field")
    public String getId() {
        return id;
    }

    @Version
    @AccessType(value="field")
    public Integer getVersion() {
        return version;
    }
}

@SuppressWarnings("serial")
@Entity
@Table(name="character")
public class KarmaCharacter extends DomainEntity {
    private String alias;
    private String lastName;
    private String firstName;

    private SortedSet<AttributeScore> attributeScores;

    public KarmaCharacter() {
        //default constructor
    }

    @Column
    @AccessType(value="field")
    public String getAlias() {
        return alias;
    }

    @Column
    @AccessType(value="field")
    public String getFirstName() {
        return firstName;
    }

    @Column
    @AccessType(value="field")
    public String getLastName() {
        return lastName;
    }

//...omitted some transient code and a collection property for brevity

    public void setAlias(String alias) {
        this.alias = alias;
    } 

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}