return new ModelAndView("request_token");
        } catch (OAuthProblemException e) {
            StringBuffer sb = new StringBuffer();
            sb.append("</br>");
            sb.append("Error code: ").append(e.getError()).append("</br>");
            sb.append("Error description: ").append(e.getDescription()).append("</br>");
            sb.append("Error uri: ").append(e.getUri()).append("</br>");
            sb.append("State: ").append(e.getState()).append("</br>");
            oauthParams.setErrorMessage(sb.toString());
            return new ModelAndView("get_authz");

        if (isEmpty(authzEndpoint)) {
            sb.append("Authorization Endpoint ");
        }

        if (isEmpty(tokenEndpoint)) {
            sb.append("Token Endpoint ");
        }

        if (isEmpty(clientId)) {
            sb.append("Client ID ");
        }

        if (isEmpty(clientSecret)) {
            sb.append("Client Secret ");
        }

        if (!REDIRECT_URI.equals(redirectUri)) {
            sb.append("Redirect URI");
        }

        String incorrectParams = sb.toString();
        if ("".equals(incorrectParams)) {
            return;
        }
        throw new ApplicationException("Incorrect parameters: " + incorrectParams);

    }

    public static boolean isEmpty(String value) {