How to enable HTTPS for standalone Wiremock

Overview:

I used wiremock standalone 2.1.11 and did the following to enable HTTPS URL for my request but to no avail:

• Studying the doc http://wiremock.org/docs/running-standalone/
• Adding --https-port but nothing happened
• Adding keystore but again no progress

The command for running the wiremock is as follows:

java -jar wiremock-standalone-2.1.11.jar --port 8920 --https-port 8921 --https-keystore /home/wiremock/keystore/clientkeystore --verbose

Note:I can connect via http port correctly

Now I would be grateful if anyone could help me find solution for HTTPS connection.