I'm attempting to be helpful here....
As I said, there are plenty of open threads on this topic in the "South Asia and the Far East" where you will likely find useful and current information. Do an advanced search for "Hainan Airlines" in title only.
Also, HNA isn't an airline, they're a private company in China that owns and runs many airlines under the HNA Group and Hainan is just one of those airlines. The OP wasn't specific about which airline. They all are different and have different contracts and working conditions... although that may change in the future.