The Chinese had a lot of trouble producing the Spey 202 as the WS9.
Even though it was under licence production from RR, they didn't have the level of technology for - at that stage - such an advanced afterburnered bypass. A main problem, I believe, was mastering turbine blade technology.
So in a game of catch-up there was a lot of reverse-engineering, and in the late 1990s China bought over 100 ex-RAF F-4 Speys. These powered the initial limited batch productions of the JH-7 (FB-7).
Finally they cracked it with the indigenous WS9A which has powered the follow-on JH-7A. China has truly benefited from the technology transfer.