Currently, registerCachedFile accepts Strings as file-paths.
This is undesirable because invalid paths are detected much later than necessary; at the moment this happens when we attempt to upload them to the blob store, i.e. during job submission, when ideally it should fail right away.
As an intermediate solution we can modify the DistributedCacheEntries to contain Paths instead of Strings. This will not require API changes but still allow earlier detection.