code: public static void runExample(
        AdManagerServices adManagerServices,
        AdManagerSession session,
        int activityGroupId,
        long advertiserCompanyId)
        throws RemoteException {
      // Get the ActivityGroupService.
      ActivityGroupServiceInterface activityGroupService =
          adManagerServices.get(session, ActivityGroupServiceInterface.class);
  
      // Create a statement to only select a single activity group by ID.
      StatementBuilder statementBuilder =
          new StatementBuilder()
              .where("id = :id")
              .orderBy("id ASC")
              .limit(1)
              .withBindVariableValue("id", activityGroupId);
  
      // Get the activity group.
      ActivityGroupPage page =
          activityGroupService.getActivityGroupsByStatement(statementBuilder.toStatement());
  
      ActivityGroup activityGroup = Iterables.getOnlyElement(Arrays.asList(page.getResults()));
  
      // Update the companies.
      activityGroup.setCompanyIds(
          Longs.concat(activityGroup.getCompanyIds(), new long[] {advertiserCompanyId}));
  
      // Update the activity group on the server.
      ActivityGroup[] activityGroups =
          activityGroupService.updateActivityGroups(new ActivityGroup[] {activityGroup});
  
      for (ActivityGroup updatedActivityGroup : activityGroups) {
        System.out.printf(
            "Activity group with ID %d and name '%s' was updated.%n",
            updatedActivityGroup.getId(), updatedActivityGroup.getName());
      }
    }
docs: Runs the example.
  
  @param adManagerServices the services factory.
  @param session the session.
  @param activityGroupId the ID of the activity group to update.
  @param advertiserCompanyId the ID of the company to associate with the activity group.
  @throws ApiException if the API request failed with one or more service errors.
  @throws RemoteException if the API request failed due to other errors.