code: public static ServiceSpecification merge(Iterable<ServiceSpecification> specs) {
          return new ServiceSpecification(
                  Streams.stream(specs).flatMap(s -> s.services().stream())::iterator,
                  Streams.stream(specs).flatMap(s -> s.enums().stream())::iterator,
                  Streams.stream(specs).flatMap(s -> s.structs().stream())::iterator,
                  Streams.stream(specs).flatMap(s -> s.exceptions().stream())::iterator);
      }
docs: Merges the specified {@link ServiceSpecification}s into one.