private static void addResponseHeaderWithOverride(
            HttpServletRequest request, HttpServletResponse response,
            String headerName, String overrideHeaderName, String value) {
        String override = request.getParameter(overrideHeaderName);

        // NPE in if value is null
        override = (override != null) ? override : value;

        if (override != null) {
            response.addHeader(headerName, override);
        }
    }
Map XML ACLs to a canned policy if an exact tranformation exists.
src/main/java/org/gaul/s3proxy/S3ProxyHandler.java