code: protected void error(HttpServletRequest httpRequest, HttpServletResponse httpResponse, Status errorStatus)
        throws ExternalAuthenticationException, IOException {
      this.error(httpRequest, httpResponse, new IdpErrorStatusException(errorStatus));
    }
docs: Method that should be invoked to exit the external authentication process with an error where the SAML status to
  respond with is given.
  
  @param httpRequest
  the HTTP request
  @param httpResponse
  the HTTP response
  @param errorStatus
  the SAML status
  @throws ExternalAuthenticationException
  for Shibboleth session errors
  @throws IOException
  for IO errors
  @see #error(HttpServletRequest, HttpServletResponse, String)
  @see #error(HttpServletRequest, HttpServletResponse, Exception)