@Override
  void idleTimeoutChanged(ExpirationAttributes oldIdleTimeout) {
    int oldTimeout = oldIdleTimeout.getTimeout();
    if (customEntryIdleTimeout != null) {
      rescheduleEntryExpiryTasks();
    }
    if (entryIdleTimeout > 0 && (oldTimeout == 0 || entryIdleTimeout < oldTimeout)) {
      rescheduleEntryExpiryTasks();
    }
    // else it's safe to let them get rescheduled lazily, as the old expiration time will cause the
    // tasks to fire sooner than the new ones.
  }
Add the Region Idle expiry task to the scheduler
geode-core/src/main/java/org/apache/geode/internal/cache/LocalRegion.java