Issue Summary

When choosing advanced options, the RSS Feed Builder does not generate a valid RSS feed.

Steps to Reproduce

1. Go to the RSS Feed Builder at https://YOUR_SITE.atlassian.net/wiki/dashboard/configurerssfeed.action
2. Check only Pages in the Type of Content;
3. Select any space from the From Space(s)
4. Click on the Advanced Options button;
5. Add a custom Feed Name;
6. Add any label to With these labels
7. Select any space from the Exclude these spaces
8. Select Modified Date
9. Set the Limit to to "10";
10. Set the Within the last to "5";
11. Check the Include Content For Pages option;
12. Click on the Create RSS Feed button;
13. In the next screen, copy the RSS feed link;
14. Go to https://validator.w3.org/feed/ and paste the RSS feed;
15. Click on the Check button;

Expected Results

The RSS Feed generated is successfully validated.

Actual Results

The https://validator.w3.org/feed/ website reports that the RSS feed is not valid and throws errors about the feed's syntax, for example:

This feed does not validate.

line 2, column 0: Missing feed element: updated [help]

<feed xmlns="http://www.w3.org/2005/Atom">
In addition, interoperability with the widest range of feed readers could be improved by implementing the following recommendation.

line 2, column 0: Missing atom:link with rel="self" [help]

<feed xmlns="http://www.w3.org/2005/Atom">

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available.