code: func (r Product_Upgrade_Request) UpdateMaintenanceWindow(maintenanceStartTime *datatypes.Time, maintenanceWindowId *int) (resp bool, err error) {
  	params := []interface{}{
  		maintenanceStartTime,
  		maintenanceWindowId,
  	}
  	err = r.Session.DoRequest("SoftLayer_Product_Upgrade_Request", "updateMaintenanceWindow", params, &r.Options, &resp)
  	return
  }
docs: // In case an upgrade cannot be performed, the maintenance window needs to be updated to a future date.