Complementing the @djechlin answer (good answer by the way!), this function call could be also used as dummy code to hold a breakpoint in an IDE when you want to stop in some specific iteration or a particular recursive call, for example:
isUserAGoat()
could be used instead of a dummy variable declaration that will be shown in the IDE as a warning and, in Eclipse particular case, will clog the breakpoint mark, making it difficult to enable/disable it. If the method is used as a convention, all the invocations could be later filtered by some script (during commit phase maybe?).
Google guys are heavy Eclipse users (they provide several of their projects as Eclipse plugins: Android SDK, GAE, etc), so the @djechlin answer and this complementary answer make a lot of sense (at least for me).