code: public static String format(String format, Object... args) {
      return String.format(Locale.ROOT, format, args);
    }
docs: Invokes String.format() using Locale.ROOT, so that local locale
  settings don't cause generated code to have characters the C compiler
  can't manage. This method shouldn't be called for error messages or
  other text displayed to the developer invoking j2objc, however.
  
  {@link https://github.com/google/j2objc/issues/698}