It's really weird a choice in the email to provide links that looked like they weren't on GitHub to redirect to the GitHub URLs... For a moment, I was wondering if they had like a self-hosted GitHub Enterprise setup or something, until I noticed the URL redirected anyways.
That's intentional. Links will contain the redirecting address on our domain so that when we move off of GH (some day; nothing lasts forever), links will continue to work.
...I can't argue with that unassailable logic. Particularly since I use the same when I insist on using my own domain for my email address now, regardless of what provider I use behind it, after the difficulty of handing out my replacement address to everyone who used to have my old Gmail account...
This strategy has saved our bacon at work more than a handful of times. All the URLs we ship in our apps point to a "lookup" server (just Nginx with a huge list of redirect rules), such that if the URL we were using in the app disappears, we can change it on the server side rather than requiring a client update.
How interesting, more and more activity? year by year
Yeah, that timeline starts towards the end of Sun's life, when investment in Java was at an ebb. Since the acquisition by Oracle, investment in Java has grown.