Firefox cuts files, whose name contains spaces, in a Struts application

public class Download extends Action {
    private static final int BUFFER_SIZE = 4096;

    public ActionForward execute(ActionMapping mapping,
		ActionForm     form,
		HttpServletRequest request,
		HttpServletResponse response) throws Exception {
        String filename = "file with spaces.pdf";
        File file =  ... // variable containing the file;
        response.setStatus(HttpServletResponse.SC_OK);
        response.setContentType(getMimeType(request, file));
        response.setHeader("Content-Type", getMimeType(request, file));
        response.setHeader("Content-Disposition","attachment; filename="+ filename);
        InputStream is = new FileInputStream(file);
        sendFile(is, response);
        return null;
   }

   protected String getMimeType(HttpServletRequest request, File file) {
        ServletContext application = super.servlet.getServletContext();
        return application.getMimeType(file.getName());
   }

   protected void sendFile(InputStream is, HttpServletResponse response) throws IOException {
       BufferedInputStream in = null;
       try {
            int count;
            byte[] buffer = new byte[BUFFER_SIZE];
            in = new BufferedInputStream(is);
            ServletOutputStream out = response.getOutputStream();
            while(-1 != (count = in.read(buffer)))
                out.write(buffer, 0, count);
            out.flush();
       } catch (IOException ioe) {
            System.err.println("IOException in Download::sendFile");
            ioe.printStackTrace();
       } finally {
            if (in != null) {
                try {
                   in.close();
                } catch (IOException ioe) { ioe.printStackTrace(); }
            }
       }
    }
}

response.setHeader("Content-Disposition","attachment; filename="" + filename + """);