code: private InternalServerErrorException internalServerError(String message, Throwable cause)
      {
          Response response = ResponseUtil.internalServerError(message, MediaType.TEXT_PLAIN_TYPE);
  
          if (cause != null)
          {
              return new InternalServerErrorException(message, response, cause);
          }
          else
          {
              return new InternalServerErrorException(message, response);
          }
      }
docs: Create an {@link InternalServerErrorException} instance having
  a response body.