docs: @Override
      public String tagKey(String key) {
          String conventionKey = NamingConvention.snakeCase.tagKey(key);
  
          String sanitized = tagKeyChars.matcher(conventionKey).replaceAll("_");
          if (!Character.isLetter(sanitized.charAt(0))) {
              sanitized = "m_" + sanitized;
          }
          return sanitized;
      }