Why/when can the track URI be `null`?

[woeful lily]

(Originated from a question on the Lavalink4NET support server) According to the Lavalink documentation, TrackInfo#uri has the type ?string, which implies the value is always present, but may be null. Are there any cases where uri is null, or is this provided for leaving the freedom of possible providers in the future, that might not have an associated URI?

[steady current]

URI didn't used to be there for V1 tracks if I recall correctly

https://github.com/lavalink-devs/lavaplayer/blob/main/main/src/main/java/com/sedmelluq/discord/lavaplayer/player/DefaultAudioPlayerManager.java#L247

Can it be null?
Sure if you encounter a V1 track

But realistically all modern sources have an uri set