The definition of "method" in 6.1 makes the now-incorrect assertion that all interface methods are abstract:

– A method, one of the following:
› A method (abstract or otherwise) declared in a class type or enum type (§8.4, §8.9.2)
› A method (always abstract) declared in an interface type or annotation type (§9.4, §9.6.1)

This could be fixed by changing the qualifiers to "abstract or concrete" and "abstract or default"; or by simply not talking about abstractness here.