I haven't seen anything definitive, but I know that cash was an option for many vendors at RAP Orlando a few weeks ago so I'd be surprised if it was a cashless event. Enjoy the event!
My suggestion, as I have been to a few shows that would take cash if you were close to the end price.
Bring a good mix of bills and stay away from 100s, unless you plan to spend in the 100s
For example, don’t hand them a 100 for a 25 dollar coral. Make sure you have 5s, 10s and 20s. Ones really aren’t needed and from what I have seen if a total comes to 302.00 for example, they will take 300 and call it a day.