This sample has been deprecated/archived meaning it's read-only and it's no longer actively maintained (more details on archiving can be found here).
There is a new sample called ClassicsKotlin in our github.com/android/tv-samples repo that covers MediaSession support, ExoPlayer media playback, TV launcher home screen channels, Content Providers, Leanback browsing / playback experience, and global search / the Google Assistant.
Please check that out instead. Thank you!