What does SSH use UDP for?

I tried it with several SSH connections from Windows to Unix and Unix to Unix and I don't get a single UDP packet on port 22. Also the server only listens on TCP.

In this thesis they tried to implement UDP for SSH transport, but they also mention that the default only uses TCP: ". OpenSSH is using TCP consistently for all its network connections and thus for its VPN feature.". The Wikipedia page might say it's UDP because the SSH developers made an initial request for UDP & TCP assignments, but the related RFC makes no mention of it.

... The SSH protocol uses or has used 22/UDP for tunneling control through TCP. If decoded properly via Wireshark and you are tunneling a connection through via either ssh-agent or tunneling remotely or locally you would notice that UDP is encapsulated within the TCP segments.