...

set JAVA_HOME=C:\Program Files\Unimus\jrejre8
set KEYTOOL=%JAVA_HOME%\bin\keytool

cd "C:\Program Files\Unimus"
"%KEYTOOL%" -genkey -alias unimus -storetype PKCS12 -keyalg RSA -keysize 2048 -keystore unimus.keystore.p12 -validity 3650

...

During the cert generation, you will be asked for the keystore password.
Input the password you with wish to use (the keystore will be generated with such password) - you will need it in the next step.

...

Generate self-signed cert:

JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
KEYTOOL=$JAVA_HOME/bin/keytool
 
cd /opt/unimus
$KEYTOOL -genkey -alias unimus -storetype PKCS12 -keyalg RSA -keysize 2048 -keystore unimus.keystore.p12 -validity 3650

...

Restart the Unimus service, and it should be available only over HTTPS.

Notes and tips

Important note: please be careful if the keystore password contains the # character.

# is used as a comment, so a password containing it will not be fully read from the configuration.
You can enclose the password in " (double quotes) if you wish to use # as a part of the password.