When converting to upper case to match English constants, use
Locale.English or things will go wrong when running on the Turkish
locale.

See http://mattryall.net/blog/2009/02/the-infamous-turkish-locale-bug

and other Google results:
https://www.google.com/search?q=java+toUpperCase+turkish&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
Merge pull request #13 from garydgregory/turkish-fix

Fix for classic toUpperCase gotcha when locale is Turkish