instant.invalidated < instant.snapshottingFinished
        !vfs.findSnapshot(location).present
        !vfs.findSnapshot("${location}/some/child").present
        !vfs.findSnapshot("${location}/some/child2").present
        vfs.findSnapshot("${location}/other/child").present
        vfs.findSnapshot("${location}/other/child2").present
    }

        Supplier<T> readFromDisk
    ) {
        return virtualFileSystem.findSnapshot(location)
            .map(snapshotProcessor)
            // Avoid snapshotting the same location at the same time
            .orElseGet(() -> producingSnapshots.guardByKey(location,
                () -> virtualFileSystem.findSnapshot(location)
                    .map(snapshotProcessor)
                    .orElseGet(readFromDisk)

            SnapshotHierarchy currentRoot = root;
            root = updateFunction.apply(currentRoot);
        });
    }

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

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

    @Override

            .store("/other/just-checking", directorySnapshotForPath("/other/just-checking"), diffListener)

        expect:
        set.findSnapshot(firstPath).present
        set.findSnapshot(secondPath).present
        set.findMetadata("/").get().type == FileType.Directory
        !set.findSnapshot("/").present

        when:
        def invalidated = set.invalidate(firstPath, diffListener)
        then:

import java.util.stream.Stream;

public interface VirtualFileSystem {

    /**
     * Returns the snapshot stored at the absolute path if it exists in the VFS.
     */
    Optional<FileSystemLocationSnapshot> findSnapshot(String absolutePath);

    /**
     * Returns the metadata stored at the absolute path if it exists.
     */
    Optional<MetadataSnapshot> findMetadata(String absolutePath);

    /**

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

    /**
     * Returns the snapshot stored at the absolute path if one exists.
     */
    default Optional<FileSystemLocationSnapshot> findSnapshot(String absolutePath) {
        return findMetadata(absolutePath)
            .filter(FileSystemLocationSnapshot.class::isInstance)
            .map(FileSystemLocationSnapshot.class::cast);
    }