Add http header for static files

[Ludovic chaplin]

Hello,

I'm using Restlet for serving some static files (img, xsl, css...).
I put all this files in a directory resource :
    final Directory root = new Directory(this.getContext(), 
STATIC_FILE_URI);
    router.attach("/", root);

I would like to add cache control http headers like Expires, 
Last-Modified...
Is there a way to add http header for this files like with the apache 
mod_header?

Thank you,
Ludovic