IssueTracker

Component used: Room
Version used: 2.2.0-alpha01
Devices/Android versions reproduced on: Pixel 3 XL / Android P

I've tried to use the new awesome Target Entity feature that introduced at 2.2.0-alpha01.
But, I encountered the Room compiler error.
It seems to happen if try inserting immutable data class using @Insert(entity = ImmutableDataClass::class)
The error message says "Cannot find setter for field.". But, the generated Dao_Impl code does not use the setter methods.
Is this a Room compiler bug?

The workaround is replacing val to var.

Here is sample codes:

```
@Database(entities = [Project::class], version = 1)
abstract class TargetEntityDatabase : RoomDatabase() {
    abstract fun projectDao(): ProjectDao
}

@Entity
data class Project(
    @PrimaryKey
    val id: Long,
    val title: String,
    @ColumnInfo(defaultValue = "''")
    val longDescription: String
)

data class ProjectMiniApiEntity(
    val id: Long,
    val title: String
)

@Dao
interface ProjectDao {
    @Insert(entity = Project::class)
    fun insertNewProject(projectMini: ProjectMiniApiEntity)
}
```

Gradle logs:

```
> Task :app:kaptDebugKotlin FAILED
e: ProjectMiniApiEntity.java:20: error: Cannot find setter for field.
    private final long id = 0L;
                       ^
e: ProjectMiniApiEntity.java:22: error: Cannot find setter for field.
    private final java.lang.String title = null;
                                   ^
```