In Spin 3.x, you could put a Vec<u8> in a Response body. Now, as far as I can tell, you have to do a FullBody::new(Bytes::from(...)) before it will let you.
This is non-obvious and is 28 extra characters, do you think I am made of keyboards.
(I know the young people are all about streaming bodies but sometimes it's useful, particularly for docs purposes, to just dump a blob in there, declare victory, and go home.)