"declaring code" means headers, or in the case of Java function specification/prototypes, right? As in "declarations". I think it's technical language twisted through legalese.
The problem is that to reimplement the spec in this case, you do have to copy the formal declarations verbatim. Whether or not those "sentences" are protected, and pass the threshold of originality [1], is what is at stake here.
The trial now is about Google's "fair use" of those APIs.