Do you mean the 4 or 6 inches or so of pipe that stick out from the flap track fairing? It is visible on quite a few photos of the prototype on this page:
Early days
From that I'd say it was modified early in the development (the fairings look different on the roll-out photos), probably as part of the drag reduction program or because the fuel spray pattern wasn't satisfactory.
That's my two cents from looking at a few photos, I'm sure someone more knowledgeable will come up with the true answer.