Information about cached file content is stored in HTTP runtime cache when caching is enabled. Cached file should be removed form disk automatically when cache is expired.

Provider should reload file content from SharePoint if it cannot open cached file in temporary folder. So you can try to remove/move/rename cached file and check if you get expected file from SharePoint.

You can set cache expiration time in seconds using VPP configuration parameter cacheExpirationTime. It is set to 10 seconds by default if it is not defined in VPP settings.

Thanks Dmytro - In our instance, it does not seem the files in the cache folder are removed all the time. It sounds like we can safely delete files from this folder and if the items we delete are active cache items, the provider should handle it.

Yes, it should get a file from SharePoint and cache it again.