Why port 22 on the official docker image?

I see that gitlab has its official docker image for the omnibus install but why in hell are they exposing port 22?

http://docs.gitlab.com/omnibus/docker/

Like what is the need for this? Why does this line have to be there?

--publish 22:22

Because it’s the default ssh port and it’s used when people push or pull a git repo via ssh.