public void disableSessionValidation() {
        if (this.service != null) {
            this.service.shutdownNow();
        }
        this.enabled = false;
    }
Creates a single thread {@link ScheduledExecutorService} to validate sessions at fixed intervals
and enables this scheduler. The executor is created as a daemon thread to allow JVM to shut down
core/src/main/java/org/apache/shiro/session/mgt/ExecutorServiceSessionValidationScheduler.java