debug jdk source can't watch variable what it is

https://www.cnblogs.com/shuaiqing/p/7525841.html

https://stackoverflow.com/questions/18255474/debug-jdk-source-cant-watch-variable-what-it-is

https://blog.csdn.net/appleprince88/article/details/21873807

http://dikar.iteye.com/blog/1452692