Perhaps it doesn't go to anything. An impish worker may have thrown it in there just for a prank. I had a coworker once who used to work in a farm machinery factory. They would occasionally throw some corn planter parts into the crate with a hay baler and just imagine people trying to put it together. In all seriousness, however, the dealer may know what it is if it is a usual Jayco item.
On edit: My Keystone Cougar has a rack very similar to this in the front compartment for extension cord/water hose/etc. I am certain this is what it is for.