code: private static void putGoogleAnalyticsTrackingIdIntoFlowScope(final RequestContext context, final String value) {
          if (StringUtils.isBlank(value)) {
              context.getFlowScope().remove(ATTRIBUTE_FLOWSCOPE_GOOGLE_ANALYTICS_TRACKING_ID);
          } else {
              context.getFlowScope().put(ATTRIBUTE_FLOWSCOPE_GOOGLE_ANALYTICS_TRACKING_ID, value);
          }
      }
docs: Put tracking id into flow scope.
  
  @param context the context
  @param value   the value