Good news is that it seems the pluggable mechanism is already there: https://github.com/droolsjbpm/jbpm/blob/master/jbpm-human-task/jbpm-human-task-war/src/main/java/org/jbpm/task/servlet/HumanTaskServiceServlet.java
You could implement your own solution using the code of DefaultEscalatedDeadlineHandler and adapt it to your needs.
Best Regards,