code: @Override
    public String getMessage() {
      StringBuilder msg = new StringBuilder("\n");
  
      msg.append(super.getMessage());
  
      if (detail != null) {
        msg.append("\n");
        msg.append(detail.getMessage());
        if (detail.getCause() != null) {
          msg.append(detail.getCause().getMessage());
        }
      }
      return msg.toString();
    }
docs: Returns the detail message, including the message from the nested exception if there is one.