code: public String getFormattedMessage(String key, Object[] args, String defaultString) {
          if (tnls != null)
              return tnls.getFormattedMessage(key, args, defaultString);
  
          return defaultString;
      }
docs: Look for a translated message using the input key. If it is not found, then
  the provided default string is returned.
  
  @param key
  @param args
  @param defaultString
  @return String