"Princess Leia (Fisher) has come into possession of the lightsaber once possessed by her father, Darth Vader, and later lost by Luke (Hamill) when Vader separated him from his arm during that “join me” duel in The Empire Strikes Back."

So this is a confirmation of the lightsaber being recovered when Luke lost his hand and his fathers light saber given to him by Obi-Wan.

If it's not the object that falls when Luke falls out the hatch possibly recovered by Ugnaughts living below then I wonder if it was recovered from the bottom of the large round shaft?

I wonder if they will let us know where it was recovered from?