code: protected String processMessage(String msg) {
      return String.format(MSG_FORMAT, Thread.currentThread().getName(), msg);
    }
docs: Provide a message for logging. This prepends the current thread to the message.
  Override this if you want to filter sensitive information, or add extra information to each
  message before dispatching.
  
  @param msg The message evaluated from the format, arguments and exceptions.
  @return The message that is logged