On March 30th, Apple announced they will require two-step verification on Apple IDs used to log into the Global Service Exchange portal. (They also announced they will require company domain email addresses for Apple IDs used for GSX but that's a topic for another day.)

If you have your JSS connected to GSX to import purchasing information, you are going to need to setup an app specific password for the JSS to log into GSX, otherwise after you enable two-step verification the JSS won't be able to logon.
Apple has a two-step verification FAQ as well as a guide on creating app-specific passwords.
Happy GSXing!
