you don't "add an obfuscator" -- you obfuscate the compiled jar so that others can't deob it. And it's still very easy to manipulate ob'd clients. (i'm not sure why any server would release a deobbed client to their playerbase -- clearly don't deserve to run a server)
Bump, still looking. I know this is out there, I had it and then lost my backups. Also if anyone has the tools (leanbows editor and such) that'd be great.