code: private static CampaignGroup createCampaignGroup(
        AdWordsServicesInterface adWordsServices, AdWordsSession session)
        throws RemoteException {
      // Get the CampaignGroupService.
      CampaignGroupServiceInterface campaignGroupService =
          adWordsServices.get(session, CampaignGroupServiceInterface.class);
  
      // Create the campaign group.
      CampaignGroup campaignGroup = new CampaignGroup();
      campaignGroup.setName("Mars campaign group #" + System.currentTimeMillis());
  
      // Create the operation.
      CampaignGroupOperation operation = new CampaignGroupOperation();
      operation.setOperand(campaignGroup);
      operation.setOperator(Operator.ADD);
  
      CampaignGroup newCampaignGroup =
          campaignGroupService.mutate(new CampaignGroupOperation[] {operation}).getValue(0);
      System.out.printf(
          "Campaign group with ID %d and name '%s' was created.%n",
          newCampaignGroup.getId(), newCampaignGroup.getName());
  
      return newCampaignGroup;
    }
docs: Creates a campaign group.