* @param refreshToken The refresh token to use for token acquisition.
     * @return The authentication result containing the access token.
     */
    public IAuthenticationResult getAccessToken(final String refreshToken) {
        final String authority = getAuthority() + getTenant() + "/";
        if (logger.isDebugEnabled()) {
            logger.debug("refreshToken: {}, authority: {}", refreshToken, authority);

            // TODO validate signiture

            final Map<String, Object> attributes = new HashMap<>();
            attributes.put("accesstoken", tr.getAccessToken());
            attributes.put("refreshtoken", tr.getRefreshToken() == null ? "null" : tr.getRefreshToken());
            attributes.put("tokentype", tr.getTokenType());
            attributes.put("expire", tr.getExpiresInSeconds());