Support main port not being set when using SSL.

[guillaume-alvarez]

When using HTTPS/SSL the 'port' may not be set from property spring.cloud.zookeeper.discovery.instance-port. In that case avoid throwing an exception and take the port at runtime.

[guillaume-alvarez]

CircleCI outputs this error:

#!/bin/sh -eo pipefail
# No configuration was found in your project. Please refer to https://circleci.com/docs/2.0/ to get started with your configuration.
# 
# -------
# Warning: This configuration was auto-generated to show you the message above.
# Don't rerun this job. Rerunning will have no effect.
false

[spencergibb]

We're migrating to GitHub actions for prs, just authorized