I discovered today the presence of this module in xwiki-platform: xwiki-platform/xwiki-platform-core/xwiki-platform-extension/xwiki-platform-extension-versioncheck at master · xwiki/xwiki-platform · GitHub
It has been apparently created by @caubin as part of [XWIKI-14778] Check periodically if a new distribution version is available - XWiki.org JIRA
There is several problems with this module:
- it’s not discoverable: it’s not bundled in XS and it’s documented in Extension Manager Application (XWiki.org) but the extension needs to be installed separately (it’s not in Extension Manager Application (XWiki.org))
- it’s not usable: notifications are targeting a group that is only present in the demo distrib (see: xwiki-platform/NewExtensionVersionAvailableEvent.java at master · xwiki/xwiki-platform · GitHub)
- this event target probably does not work anymore since a few versions (at least 12.x and probably even before that): as @lucaa spotted those targets should be absolute serialized references
Moreover the way for doing it would be probably different with the index of extensions introduced by @tmortagne and note that [XWIKI-14666] Notify administrators when a new version of the platform is available - XWiki.org JIRA is still open today.
So for all those reasons I propose that we just move this module to the attic.