CLI outputs a cryptic error message when a custom server address doesn't contain protocol and port number

[mnegacz]

Axon Server CLI outputs a cryptic error message:

Error processing command 'init-cluster': null

To reproduce the error, append a custom AS address without protocol and a port number to the command:

java -jar axonserver-cli.jar init-cluster -S example.org

Above invocation results in the org.apache.http.client.ClientProtocolException and null in the message.

The error message should allow identifying the problem at hand