interface FileSystemLocationSnapshotVisitor {
        default void visitDirectory(DirectorySnapshot directorySnapshot) {};
        default void visitRegularFile(RegularFileSnapshot fileSnapshot) {};
        default void visitMissing(MissingFileSnapshot missingSnapshot) {};
    }

    interface FileSystemLocationSnapshotTransformer<T> {
        T visitDirectory(DirectorySnapshot directorySnapshot);

    }

    @Override
    public void visitLeafElement(FileSystemLeafSnapshot snapshot) {
        delegate.visitLeafElement(snapshot);
    }

    @Override
    public void visitDirectory(DirectorySnapshot directorySnapshot) {
        delegate.visitDirectory(directorySnapshot);
    }

    public void markCurrentLevelAsFiltered() {
        isCurrentLevelUnfiltered.removeLast();
        isCurrentLevelUnfiltered.addLast(false);
    }

        }
    }

    @Override
    public void accept(FileSystemLocationSnapshotVisitor visitor) {
        visitor.visitDirectory(this);
    }

    @Override
    public <T> T accept(FileSystemLocationSnapshotTransformer<T> transformer) {
        return transformer.visitDirectory(this);
    }

    @VisibleForTesting
    public ImmutableList<FileSystemLocationSnapshot> getChildren() {

    void visitLeafElement(FileSystemLeafSnapshot snapshot);

    void visitDirectory(DirectorySnapshot directorySnapshot);

    /**
     * Method to call after having visited all the entries of a directory.
     *

            outputFileSnapshot.accept(entrySnapshot -> {
                entrySnapshot.accept(new FileSystemLocationSnapshotVisitor() {
                    @Override
                    public void visitDirectory(DirectorySnapshot directorySnapshot) {
                        recordOutputSnapshot(directorySnapshot);
                    }

                    @Override

            DirectorySnapshotBuilder.EmptyDirectoryHandlingStrategy.INCLUDE_EMPTY_DIRS
        )
        children.each { snapshot ->
            if (snapshot instanceof DirectorySnapshot) {
                builder.visitDirectory(snapshot)
            } else {
                builder.visitLeafElement(snapshot)
            }
        }
        return builder.leaveDirectory()
    }

    }

    @Override
    public void visitLeafElement(FileSystemLeafSnapshot snapshot) {
        collectEntry(snapshot);
    }

    @Override
    public void visitDirectory(DirectorySnapshot directorySnapshot) {
        collectEntry(directorySnapshot);
    }

    @Override
    public FileSystemLocationSnapshot leaveDirectory() {

    public static long getLength(FileSystemLocationSnapshot snapshot) {
        return snapshot.accept(new FileSystemLocationSnapshot.FileSystemLocationSnapshotTransformer<Long>() {
            @Override
            public Long visitDirectory(DirectorySnapshot directorySnapshot) {
                return 0L;
            }

            @Override
            public Long visitRegularFile(RegularFileSnapshot fileSnapshot) {

            SnapshotVisitResult result;
            boolean forceInclude = snapshot.accept(new FileSystemLocationSnapshotTransformer<Boolean>() {
                @Override
                public Boolean visitDirectory(DirectorySnapshot directorySnapshot) {
                    return root;
                }

                @Override
                public Boolean visitRegularFile(RegularFileSnapshot fileSnapshot) {

            boolean newContent = snapshot.accept(new FileSystemLocationSnapshot.FileSystemLocationSnapshotTransformer<Boolean>() {
                @Override
                public Boolean visitDirectory(DirectorySnapshot directorySnapshot) {
                    // Check if a new directory appeared. For matching directories don't check content