Our friends at Jedi News were the first to say that Jessica Henwick was cast in Star Wars: The Force Awakens back in late November. Not much information followed after that. Sometime last month we were able to figure out who Henwick was playing and some information on her ideas regarding how galactic history unfolded and her perception of a key player in it.
However, Henwick is still not officially confirmed for Star Wars. In this video, Jessica Henwick poorly denies being involved with Star Wars: The Force Awakens at 3:39:
That weak denial is the best confirmation ever. Thanks to AniSkyLover for the heads up on the JC forums!