Turkpilot, it's simple. The contract you are about to sign will be changed on a whim, without consultation with you or anyone else. This has already happened and has had a major financial impact on the pilots of this group of airlines.
There is a pilots association - EAPA - which in the case of HKE has a membership of at least 70%, but HKE management refuse to talk to them or recognise them. It is a legally registered Union in Hong Kong.
If you worked in THY before you may be used to having no union representation, or having management ram contract changes down your throat, so this may or may not actually bother you. It's your decision.
For the record - the pilots employed by HKE/HKA in Hong Kong are probably the cheapest A320/330 pilots anywhere in China, on the worst contract terms and conditions in China.