*/
    Optional<MetadataSnapshot> findMetadata(String absolutePath);

    /**
     * Returns all root snapshots in the hierarchy below {@code absolutePath}.
     */
    Stream<FileSystemLocationSnapshot> findRootSnapshotsUnder(String absolutePath);

    /**
     * Snapshots and stores the result in the VFS.
     *
     * If the snapshotted location is invalidated while snapshotting,

    @Override
    public Optional<MetadataSnapshot> findMetadata(String absolutePath) {
        return root.findMetadata(absolutePath);
    }

    @Override
    public Stream<FileSystemLocationSnapshot> findRootSnapshotsUnder(String absolutePath) {
        return root.rootSnapshotsUnder(absolutePath);
    }

    @Override

    }

    private FileSystemLocationSnapshot snapshot(String location, SnapshottingFilter filter) {
        ImmutableMap<String, FileSystemLocationSnapshot> previouslyKnownSnapshots = virtualFileSystem
            .findRootSnapshotsUnder(location)
            .collect(ImmutableMap.toImmutableMap(
                FileSystemLocationSnapshot::getAbsolutePath,
                Function.identity()
            ));