Promotes the changes in a draft back to the base campaign. This method returns a Long Running Operation (LRO) indicating if the Promote is done. Use google.longrunning.Operations.GetOperation to poll the LRO until it is done. Only a done status is returned in the response. See the status in the Campaign Draft resource to determine if the promotion was successful. If the LRO failed, use CampaignDraftService.ListCampaignDraftAsyncErrors to view the list of error reasons. List of thrown errors: AuthenticationError AuthorizationError CampaignDraftError HeaderError InternalError QuotaError RequestError