docs: private static String genGoogMsgPlaceholderName(String placeholderName) {
  
      Matcher suffixMatcher = UNDERSCORE_NUMBER_SUFFIX.matcher(placeholderName);
      if (suffixMatcher.find()) {
        String base = placeholderName.substring(0, suffixMatcher.start());
        String suffix = suffixMatcher.group();
        return CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, base) + suffix;
      } else {
        return CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, placeholderName);
      }
    }