Originally Posted by
bennos
That was my guess, too. Whatever it is, it seems oriented towards the Y cabin, as it is across from a lav that seems to serve the forward part of the Y cabin. (There is another lav by 1L that appears to be for the premium cabin.)
here are my other guesses for this "secret" room:
(1) shower for business class passengers
(2) dressing room
(3) espresso station
(4) fully-stocked bar
(5) oven of freshly-made pizza or chocolate cookies