That if you sue Facebook for patent infringement or if you sue any party for patent infringement related to use of (or modification you make to) Facebook "Software" then the license granted to you to use said Software will terminate.
Whoah. I wasn't aware there was an issue. I'd like to get someone from FB to comment on this! Seems like an unfortunate poison pill - and perhaps the explaination as to why FB released all this React infrastructure, as leverage (although I can't help but think that any organization worth suing could afford to port an app from React to something similar).
https://code.facebook.com/posts/1639473982937255/updating-ou...
https://github.com/facebook/react/commit/b8ba8c83f318b84e429...