code: private static BiddingStrategyConfiguration getAdGroupBiddingStrategyConfiguration(
        AdWordsServicesInterface services, AdWordsSession session, Long adGroupId)
        throws ApiException, RemoteException {
      AdGroupServiceInterface adGroupService = services.get(session, AdGroupServiceInterface.class);
  
      Selector selector = new SelectorBuilder()
          .fields(
              AdGroupField.Id,
              AdGroupField.BiddingStrategyType,
              AdGroupField.BiddingStrategyId,
              AdGroupField.BiddingStrategyName)
          .equalsId(adGroupId).build();
  
      AdGroupPage adGroupPage = adGroupService.get(selector);
  
      if (adGroupPage.getEntries() == null || adGroupPage.getEntries().length == 0) {
        throw new IllegalArgumentException("No ad group found with ID " + adGroupId);
      }
  
      AdGroup adGroup = adGroupPage.getEntries(0);
  
      Preconditions.checkState(adGroup.getBiddingStrategyConfiguration() != null,
          "Unexpected state - ad group ID %s has a null BiddingStrategyConfiguration", adGroupId);
      return adGroup.getBiddingStrategyConfiguration();
    }
docs: Retrieves the {@link BiddingStrategyConfiguration} of an ad group.
  
  @param services the AdWordsServices
  @param session the session to use for the request
  @param adGroupId the ad group ID
  @return the non-null BiddingStrategyConfiguration of the ad group