UTF 8 message properties in Keycloak

How can I render messages using

${msg('...')}

in UTF-8?

Currently, I have an issue that special characters arent being shown properly.

E.g. I’m getting just ????????? instead of the actual string.

I assumed that Keycloak ie Wildfly uses java.util.ResourceBundle, ie I expected Keycloak would load UTF-8 chars from msg property files - but this doesn’t seem to be the case.

What’s the best practice for having utf-8 chars in message properties?