This is unfortunate, but t least it's nothing serious.
I'm not the biggest fan of Hayward as a player - I don't dislike is game by any means, it just doesn't excite me. He's a bit too "Al Horford" like in his demeanour - too nice, laid back, polite, unselfish. It's like the guy doesn't have an aggressive bone in his body. He's a very gifted and skilled player and I can only imagine how good he COULD be if he had the mentality of say, a Jimmy Butler - he'd be an absolute stud.
That being said he seems like a genuine nice guy, and you hate to see a good guy have to go through as many setbacks as he has the past few years. hope he's able to stay healthy through the rest of this contract.