Isn’t that a bit like saying cars don’t drive unless a driver gets in them?
This comes down to what is and is not copyrightable. 'Code', whatever that is, very obviously is copyrightable - hence licensing. 'APIs' are now being separated from code by Google to support their claim that they did not violate Oracle's copyright.
To me, if I write a program under license X, it is strange to me that someone can reimplement my program's API under an incompatible license Y. To me, that violates my license, and software licenses are enforced via copyright protection.
Honestly, given that I literally write Java code for a living and think this case is mega confusing (granted, I've spent roughly 6 minutes reading about it), I am skeptical about the SC's ability to render a sensible verdict. But, meh, maybe it really can be abstracted out a legal principle.
How? The same exact way I own copyright to all of the code I write. It's the same exact system.
Yes, someone could copyright those if they weren't fundamental, obvious, and preexisting. The same way that if I write a novel new implementation of a String it is copyrighted under whatever license I choose. The same way that a new codec is copyrighted, etc.
It just seems a bit funny that the example you give to point out how obvious this standard must be is an implementation, not an interface. It would be weird to me that if I created a different String implementation with the same interfaces as your, that is prohibited.
I guess that with Java it's a little bit more straightforward, because the interface is a file that you must have created. But what if I create EvenBetterInterface and convince people to swap it out in their dependency injection and use my implementation, which otherwise has the same interfaces as yours? I feel that the interfaces they are talking about are supposed to be more that classical type of interface (a definition/promise with NO implementation details but assurance of functionality), and not the straight up Java (jesus christ, im sorry) "implementation" of an interface.