What are all built-in expiry classes available?

Hi,

I understand there is a configuration for  custom expiry.

<custom-expiry>
                        <class-name>custom.expiry</class-name>
</custom-expiry>

For our internal uses, Like to override and provide different expiries like (NeverExpireExpiry, ImmediateExpireExpriy, etc..).

Are there any built-in expiry classes that can be used. if so, what are all different built-in expiry mechanism available?

Regards

Nash