public Thread newThread(Runnable r) {
                    Thread thread = new Thread(r);
                    thread.setDaemon(true);
                    thread.setName(threadNamePrefix + count.getAndIncrement());
                    return thread;
                }
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