The source/dest file pair from zipFolders.
The sync direction.
How to compare files for differences.
Policy for destination-only files.
Retention period when keepMode is 'keep-days'.
Current time in milliseconds, used for keep-days calculation.
Factory to create the concrete action objects.
Tolerance for the comparison.
Converts a paired source/dest tuple into zero or more sync actions based on the sync direction, compare mode, and keep policy.