plain / text or application / json ?
I can not find any mention of this, today my google-fu is weak.
He does not mention this in this revision of the original map, which I see. https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit?hl=en_US&pli=1&pli=1
The Google JavaScript CDN serves the jQuery source map as application/json .
application/json