code: @RequestMapping(value="/{providerId}", method=RequestMethod.GET, params="error")
  	public RedirectView oauth2ErrorCallback(@PathVariable String providerId, 
  			@RequestParam("error") String error, 
  			@RequestParam(value="error_description", required=false) String errorDescription,
  			@RequestParam(value="error_uri", required=false) String errorUri,
  			NativeWebRequest request) {
  		Map<String, String> errorMap = new HashMap<String, String>();
  		errorMap.put("error", error);
  		if (errorDescription != null) { errorMap.put("errorDescription", errorDescription); }
  		if (errorUri != null) { errorMap.put("errorUri", errorUri); }
  		sessionStrategy.setAttribute(request, AUTHORIZATION_ERROR_ATTRIBUTE, errorMap);
  		return connectionStatusRedirect(providerId, request);
  	}
docs: Process an error callback from an OAuth 2 authorization as described at https://tools.ietf.org/html/rfc6749#section-4.1.2.1.
  Called after upon redirect from an OAuth 2 provider when there is some sort of error during authorization, typically because the user denied authorization.
  @param providerId the provider ID that the connection was attempted for
  @param error the error parameter sent from the provider
  @param errorDescription the error_description parameter sent from the provider
  @param errorUri the error_uri parameter sent from the provider
  @param request the request
  @return a RedirectView to the connection status page