code: static List<String> string(String name, @Nullable String value) {
      if (!Strings.isNullOrEmpty(value)) {
        return Arrays.asList("--" + name, value);
      }
      return Collections.emptyList();
    }
docs: Produces the flag form of a string value.
  
  @return {@code [--name, value]} or {@code []} if value is null.