I've looked through the official documentation and I can't find anywhere that states you can expand java properties or environment variables in JAAS configuration files.
Is this supported, and if so is there any documentation that describes it?
System properties can be used in jaas.conf according to the Oracle documentation: https://docs.oracle.com/javase/8/docs/api/javax/security/auth/login/Configuration.html
If a String in the form, ${system.property}, occurs in the value, it will be expanded to the value of the system property.