Question: when does "onResourceReady" provide a onResourceReady that's not BitmapDrawable ?

[AndroidDeveloperLB]

for the RequestListener interface, in "resource" argument :

public boolean onResourceReady(final Drawable resource, final Object model, final Target<Drawable> target, final DataSource dataSource, final boolean isFirstResource)

https://bumptech.github.io/glide/javadocs/410/com/bumptech/glide/request/RequestListener.html#onResourceReady-R-java.lang.Object-com.bumptech.glide.request.target.Target-com.bumptech.glide.load.DataSource-boolean-

Is it perhaps only for when I load resources from the app itself ?