Use jukebox_song data for music instead of disc items in versions 1.21+

What feature do you want to see added?

As of 1.21, music discs are now data driven, allowing data packs to add more music disc definitions. Instead of just prepending "music_disc_" to whatever id you provide and checking it as an item (that's what I assume this plugin does right now anyways) it should look up the jukebox_song data for a provided id in newer versions. This will make adding custom music to servers incredibly easy.

It would also be nice to be able to customize the music menu that appears when you run /plot music, but fortunately that's something that can easily be done with a custom menu running /plot flag set music anyways, so that's not as important. But the inability to add any sort of custom music to plots is really annoying and this could easily address that issue.

Are there any alternatives?

No.

Anything else?

jukebox_song data provides a sound event and song length, I assume the song length value is why this plugin requires music to be from music discs instead of just allowing any sound event.

Start by locating the existing /plot music handling and the code that derives music-disc item IDs, then inspect how version 1.21+ data-driven jukebox_song definitions are exposed. Confirm how a provided ID maps to its sound event and song length. Done means custom jukebox_song IDs can be used for plot music on 1.21+ without breaking older-version behavior.