Build error depending on room-compiler version

If I use the room-compiler version that’s listed in the book

kapt ''

then everything works fine. However, if I follow the warning and upgrade to the newer version

kapt ''

then I receive the following build error:

criminalintentbnr4k/database/ error: cannot find symbol
  symbol:   class ValidationResult
  location: class RoomOpenHelper

Obviously the newer version is not final, but any insight what would have changed to make the ValidationResult class be relocated?