wicket filter per host

    @WebFilter(urlPatterns = "/*")
    public static class Filter implements IWebApplicationFactory, javax.servlet.Filter {

        private final Map<String, WicketFilter> filters = new HashMap<String, WicketFilter>();
        private final ThreadLocal<String> hosts = new ThreadLocal<String>();
        private FilterConfig config;

        public Filter() {
            System.setProperty("wicket.configuration", DEPLOYMENT);
        }

        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            this.config = filterConfig;
        }

        @Override
        public void destroy() {
            for (WicketFilter w : filters.values()) {
                w.destroy();
            }
            filters.clear();
        }

        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
            hosts.set(request.getServerName());
            try {
                getFilterForHost().doFilter(request, response, chain);
            } finally {
                hosts.remove();
            }
        }

        private WicketFilter getFilterForHost() throws ServletException {
            String host = hosts.get();
            if (!filters.containsKey(host)) {
                WicketFilter w = new WicketFilter() {

                    @Override
                    protected IWebApplicationFactory getApplicationFactory() {
                        return Filter.this;
                    }
                };
                w.init(config);
                filters.put(host, w);
            }
            return filters.get(host);
        }

        @Override
        public WebApplication createApplication(WicketFilter wf) {
            return new WicketApp(hosts.get());
        }