/**
     * Returns the underlying HttpServletRequest from a reslet Request object.
     * <p>
     * Note that this only returns a value in teh case where the reslet 
     * request/call is originating from a servlet.
     * </p>
     * @return The HttpServletRequest, or null.
     */
    public HttpServletRequest getServletRequest( Request request ) {
        if ( request instanceof HttpRequest ) {
            HttpRequest httpRequest = (HttpRequest) request;
            if ( httpRequest.getHttpCall() instanceof ServletCall ) {
                ServletCall call = (ServletCall) httpRequest.getHttpCall();
                return call.getRequest();
            }
        }
        
        return null;
    }