Back to 2009, beginning of social network for mobile platforms - which should work via bluetooth ID, my first working Java experience.
Platform JavaEE, Netty for connections, MySQL - may be few other interesing features.
Well, at least even being alone as a programmer there, i got some new experience.
Can say that http://netty.io wasn't easy for me to start using, well kinda another stack - compare at that time with Python Twisted with their deferred conception (ooh.. was tough)
But it was 7 years ago, so welcome to the legacy