Oracle will say it's the same book, there are always grey areas. You can't copyright a love story between a boy and a girl, but you can copyright a particular book on it. So if the API is copyrightable, then even though it was implemented differently, isn't it using their property?
What Google did was remove a chapter here and there and add a couple of their own chapters -- in this book analogy, clearly copyright infringement.
The actual quotes used in the slides is "you form an API using those parts of speech in the same way I'd write a technical paper using, you know, nouns, verbs, objects, so on." In other words, you couldn't copyright java.lang package name itself (an adjective say) but you could copyright the collection of everything in it (as like technical paper).
I'm astounded that this is in Google's slides. Slide 12 basically says the Java API, taken as a whole, is copyrightable.