title: Delete items using Apple's new api NSFileProviderReplicatedExtension
body: <p>We are using Apple's new api NSFileProviderReplicatedExtension to implement a file provider extension.
  We can use this extension to synchronize files from a remote file server.When there are changes on the server，we can signal <code>workingset</code> to update the local copy.
  But when a directory with many files is deleted on the server, we can't delete this directory by calling <code>observer.didDeleteItems</code>.Can someone give me some advice?
  The Apple's documents is here:<a href="https://developer.apple.com/documentation/fileprovider/replicated_file_provider_extension/synchronizing_the_file_provider_extension" rel="nofollow noreferrer">enter link description here</a></p>