There was some drama about China possibly obtaining US stealth technology during Yugoslavia. There is an even more crazy conspiracy theory going on that this is why we bombed their embassy.
http://jpk.buaa.edu.cn/2007jpk/bjsjpk/fjztsj/jxlx/jxlx.htm
11m35s
at BUAA that piece in question is in public display
http://www.hobbyshanghai.com.cn/data/attachment/forum/201205...
The mumblings I've heard is that the Chinese stole blueprints from the F-22 project. I don't have a URL handy at the moment, as I'm not near a web browser.
Besides, you can Google a sized-referenced picture of an F-22 from every angle. It's a relatively well-documented airframe.
http://www.telegraph.co.uk/news/worldnews/asia/pakistan/8701...
Though, it is unclear if China was behind the attack.