Scala与JPA和GAE

Question

我想用scala编写我的dtos，但它似乎不起作用。当我想在本地网络服务器上解密web应用程序时，我收到以下消息：

Caused by: org.datanucleus.metadata.InvalidMetaDataException: 
Class de.cassys.gkasse.model.Application has application-identity 
and no objectid-class specified yet has 0 primary key fields. 
Unable to use SingleFieldIdentity.

令人困惑的是，我已经定义了一个主键字段。看看这段代码：

@Table(name = "applications")
@Entity
class Application(
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Key = null,
    var currentVersion: String = null,
    var certificate: Array[Byte] = null,
    var created: Date = null,
    var exec: Array[Byte] = null) 

我该怎么办？