This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
The warning doesn't mean you need to recompile it. It's just a hint that if you recompile with these options, you see why this warning is being shown. Since you're using legacy code it's probably something with raw types.