contentEntityObject.isNew method is implemented as comparing the created date with the last modification date. if they are the same, entity is considered new. This check is used to determine if the rss item has a title of 'News item created' or 'News item edited'. This doesn't work for news items as their modification date seams to always be set a few seconds after creation. The side affect of this is that all news item rss items will report updates on news items (none will have the 'created' title).