Citation?
As far as i know, it was created almost entirely by a team at Google, and the agreement to get Apple on board was to not publicize this fact. Which is really sad, because then John Gruber then went off and credited their work to Apple without bothering to fact check it.
IIRC, Apple was not even at the USB meeting where it was first presented.
I'm sure post coming on board Apple contributed, but yeah.
(Various xooglers and others have confirmed all this publicly now, AFAIK)