First I had to allow the Docker Bridge for my Docker Network to route traffic to the host. This is a bit cumbersome as the id for the network bridge for my Docker network is generated by Docker. I had to manually add a rule to iptables.
I am using letsencrypt server certificates and the letsencrypt ca is not part of the default java truststore. There for I had to add it to the following truststore: $JAVA_HOME/jre/lib/security/cacerts.