Room. Создание простейшего примера

В чём ошибка и как можно исправить?

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.root.pets/com.example.root.pets.MainActivity}: java.lang.RuntimeException: cannot find implementation for com.example.root.pets.AppDatabase. AppDatabase_Impl does not exist

@Entity
class Person {
    @PrimaryKey
    internal var name: String? = null
    internal var age: Int = 0
    internal var favoriteColor: String? = null
}

@Dao
interface PersonDao {
    // Получение всех Person из бд
    @get:Query("SELECT * FROM person")
    val allPeople: List<Person>
    // Добавление Person в бд
    @Insert
    fun insertAll(vararg people: Person)
    // Удаление Person из бд
    @Delete
    fun delete(person: Person)
    // Получение всех Person из бд с условием
    @Query("SELECT * FROM person WHERE favoriteColor LIKE :color")
    fun getAllPeopleWithFavoriteColor(color: String): List<Person>
}

@Database(entities = arrayOf(Person::class /*, AnotherEntityType.class, AThirdEntityType.class */), version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract val personDao: PersonDao
}

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val myThread = Thread(object : Runnable {
        override fun run() {
            var db = Room.databaseBuilder(getApplicationContext(),
                    AppDatabase::class.java, "populus-database4").build()
            val everyone = db.personDao
            val person = Person()
            person.name = "John Smith"
            person.age = 10000
            person.favoriteColor = "black"
            everyone.insertAll(person)
            val persons = everyone.allPeople
            Log.d("111", "${everyone.allPeople[0].name}")
        }
    })
    myThread.start()
    }
}