Successful connect to a closed port with FirewallD
You don't see these in firewalld because Docker opens the ports itself, outside of firewalld.
To see what Docker is doing, run:
iptables -L DOCKER
iptables -t nat -L DOCKER
Docker will open firewall ports itself for any port your containers EXPOSE, unless you explicitly disable this. It also allows containers which need to communicate with each other to do so, so you should leave this enabled unless you really know what you're doing.