very briefly touched on in the Jiangxi aerospace industry conference speech given by Liu Daxiang, one of the key person in charge of Chinese aero engine development. He confirmed the fourth generation turbofan with thrust to weight ratio of 10 for J-20, while not yet in service, is currently in test flight. The fifth generation turbofan with thrust to weight ratio of 11-12 is in development.

His speech is on the aero engine development for fighter jet as well as large aircraft such as military transport and civilian jet liner. It's very clear that the engine components are domestically developed through R&D effort. These are not off-the-shelf components which you can buy for DIY.