Custom Crontab in stead of scheduler?

In follow up of certifiate rollover question…

Anyone know how to create a crontab via java code in keycloak ?
So not a scheduler (SPI / timer) but a crontab that follows the crontab regex.
The purpose is to set a crontab for every individual identity provider, instead of creating a scheduler that runs ever x seonds… I do not find any examples how to to do this in keycloak …
Probably because of cluster it needs to use kind of cluster awareness or mechanisme so it knows it runs only once in the cluster on the configured time.