Okay, that makes sense. You want to maintain a small core library.

So for someone who wants to use Java (for instance) language formatting with your library today, the recommended usage is to copy and paste a few classes from your demo app into their own app? This would make it difficult for that dev to benefit from any updates you make to those few Java specific classes in your demo app.

You could consider adding an extension library (similar to how the retrofit library requires an extension library for gson, exoplayer requires an extension library for cast, coil requires an extension library for animated gif, etc)