Migration from Sync API v1 to Core API v2

The API v2 SDKs don't provide caching layers for you like the Sync SDKs did, but if you are caching file content locally like that, the rev value you mentioned can be used to keep track of changes. That is, when you store a copy of a file locally, store the rev value for that copy as well. When you see the remote rev value as different from the local one, you know that the file changed and you should download the new version.

For example, when using listFolderContinue, you'll get a list of Metadata entries, where you can see if there's a new version of a file you cached.