Duplicate of How do you use carousel/multiple images in the gmail promotion annotations? but has the question is simply associated with the gmail-promo-tabs tag and not the gmail-api asked by the official Gmail API support I thought it's maybe not visible.
The problem is the same, I saw examples of multiples images carousel in Gmail including CatalogCardLayout (Carousel Images) for Gmail Annotation but I don't found any documentation about it.
I want to know if this functionality still exist and where is the documentation ?
