docs: private void listGreetings(String guestbookName) throws DatastoreException {
      Query.Builder query = Query.newBuilder();
      query.addKindBuilder().setName(GREETING_KIND);
      query.setFilter(makeFilter(KEY_PROPERTY, PropertyFilter.Operator.HAS_ANCESTOR,
          makeValue(makeKey(GUESTBOOK_KIND, guestbookName))));
      query.addOrder(makeOrder(DATE_PROPERTY, PropertyOrder.Direction.DESCENDING));
  
      List<Entity> greetings = runQuery(query.build());
      if (greetings.size() == 0) {
        System.out.println("no greetings in " + guestbookName);
      }
      for (Entity greeting : greetings) {
        Map<String, Value> propertyMap = greeting.getProperties();
        System.out.println(
            DatastoreHelper.toDate(propertyMap.get(DATE_PROPERTY)) + ": " +
            DatastoreHelper.getString(propertyMap.get(USER_PROPERTY)) + " says " +
            DatastoreHelper.getString(propertyMap.get(MESSAGE_PROPERTY)));
      }
    }