code: private static void createCustomizerFeedItems(AdWordsServicesInterface adWordsServices,
        AdWordsSession session, List<Long> adGroupIds, AdCustomizerFeed adCustomizerFeed)
        throws RemoteException {
      // Get the FeedItemService.
      FeedItemServiceInterface feedItemService =
          adWordsServices.get(session, FeedItemServiceInterface.class);
  
      List<FeedItemOperation> feedItemOperations = new ArrayList<>();
  
      DateTime now = new DateTime();
  
      DateTime marsDate = new DateTime(now.getYear(), now.getMonthOfYear(), 1, 0, 0);
      feedItemOperations.add(
          createFeedItemAddOperation(
              "Mars", "$1234.56", marsDate.toString("yyyyMMdd HHmmss"), adCustomizerFeed));
  
      DateTime venusDate = new DateTime(now.getYear(), now.getMonthOfYear(), 15, 0, 0);
      feedItemOperations.add(
          createFeedItemAddOperation(
              "Venus", "$1450.00", venusDate.toString("yyyyMMdd HHmmss"), adCustomizerFeed));
  
      FeedItemReturnValue feedItemReturnValue = feedItemService.mutate(
          feedItemOperations.toArray(new FeedItemOperation[feedItemOperations.size()]));
  
      for (FeedItem addedFeedItem : feedItemReturnValue.getValue()) {
        System.out.printf("Added feed item with ID %d.%n", addedFeedItem.getFeedItemId());
      }
  
      // Add feed item targeting to restrict the feed item to specific ad groups.
      restrictFeedItemToAdGroup(
          adWordsServices, session, feedItemReturnValue.getValue(0), adGroupIds.get(0));
      restrictFeedItemToAdGroup(
          adWordsServices, session, feedItemReturnValue.getValue(1), adGroupIds.get(1));
    }
docs: Creates FeedItems with the values to use in ad customizations for each ad group in
  <code>adGroupIds</code>.