I saw this thread about using multiple images in the gmail annotations but never found any documentation on how to accomplish it. I was hoping the google team in charge of this feature could shed some light on how to code this in JSON-LD and point me to documentation on it if it exists!
example screenshot of a promo email that shows multiple images
It is called Product Carousel annotation. More here https://developers.google.com/gmail/promotab/overview#product-carousel