> difference between the API code (where the names are mangled and meaningless) and the API design.
API Code = header file or interface files or source code artifacts you need to include in order to make use of the system underlying the API.
API design = a behavioral specification which the system represented by the API implements
> In this case the naming is an important factor, as that is the competitive advantage leveraged by Google in copying Oracle's Java API.
My point is it's an important factor in the design specification, not the code. This makes it an invention. Inventions cannot be copyrighted per Baker; they can however be patented.
> They were able to tap into a developer resource who was familiar with the style, naming and conventions of Java
The Baker case specifically addresses this point by saying embodied practices cannot be copyrighted. Java isn't a book, it's an invention so the proper avenue for protection is a patent and not copyright.
> The API is the interface between the human and the code, and so copying a familiar interface design can be an advantage when building a platform
Again this would be arguable as a patent infringement, but here we are discussing copyright and not patents. What you're describing applies to design patents IMO. [IANAL]