docs: public static AccessTokenSource getSource(Bundle bundle) {
          Validate.notNull(bundle, "bundle");
          if (bundle.containsKey(TokenCachingStrategy.TOKEN_SOURCE_KEY)) {
              return (AccessTokenSource) bundle.getSerializable(TokenCachingStrategy.TOKEN_SOURCE_KEY);
          } else {
              boolean isSSO = bundle.getBoolean(TokenCachingStrategy.IS_SSO_KEY);
              return isSSO ? AccessTokenSource.FACEBOOK_APPLICATION_WEB : AccessTokenSource.WEB_VIEW;
          }
      }