code: public static void runExample(AdWordsServicesInterface adWordsServices, AdWordsSession session,
        List<Long> campaignIds, Long labelId) throws RemoteException {
      // Get the CampaignService.
      CampaignServiceInterface campaignService =
          adWordsServices.get(session, CampaignServiceInterface.class);
  
      // Create label operations.
      List<CampaignLabelOperation> operations = new ArrayList<>(
          campaignIds.size());
      for (Long campaignId : campaignIds) {
        CampaignLabel campaignLabel = new CampaignLabel();
        campaignLabel.setCampaignId(campaignId);
        campaignLabel.setLabelId(labelId);
  
        CampaignLabelOperation operation = new CampaignLabelOperation();
        operation.setOperand(campaignLabel);
        operation.setOperator(Operator.ADD);
  
        operations.add(operation);
      }
  
      // Display campaign labels.
      for (CampaignLabel campaignLabelResult : campaignService.mutateLabel(
          operations.toArray(new CampaignLabelOperation[operations.size()])).getValue()) {
        System.out.printf("Campaign label for campaign ID %d and label ID %d was added.%n",
            campaignLabelResult.getCampaignId(), campaignLabelResult.getLabelId());
      }
    }
docs: Runs the example.
  
  @param adWordsServices the services factory.
  @param session the session.
  @param campaignIds the IDs of the campaigns to which the label will be added.
  @param labelId the ID of the label to attach to campaigns.
  @throws ApiException if the API request failed with one or more service errors.
  @throws RemoteException if the API request failed due to other errors.