无法获得Room DB与Kotlin一起运行

你可以在我的回购中find所有的代码： https ： //github.com/NWuensche/BookNotes/tree/add-room-db

我得到以下错误：

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.nwuensche.booknotes, PID: 22753 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nwuensche.booknotes/com.nwuensche.booknotes.MainActivity}: java.lang.RuntimeException: cannot find implementation for com.nwuensche.booknotes.model.AppDatabase. AppDatabase_Impl does not exist at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2684) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2751) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1496) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6186) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779) Caused by: java.lang.RuntimeException: cannot find implementation for com.nwuensche.booknotes.model.AppDatabase. AppDatabase_Impl does not exist at android.arch.persistence.room.Room.getGeneratedImplementation(Room.java:92) at android.arch.persistence.room.RoomDatabase$Builder.build(RoomDatabase.java:454) at com.nwuensche.booknotes.MainActivity.onCreate(MainActivity.kt:35) at android.app.Activity.performCreate(Activity.java:6684) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2637) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2751) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1496) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6186) 

我究竟做错了什么？ 谢谢你帮助我