private void addDefaultHandlers(Server server, Environment environment, MetricRegistry metrics) {
        final JerseyEnvironment jersey = environment.jersey();
        final Handler applicationHandler = createAppServlet(
                server,
                jersey,
                environment.getObjectMapper(),
                environment.getValidator(),
                environment.getApplicationContext(),
                environment.getJerseyServletContainer(),
                metrics);
        final Handler adminHandler = createAdminServlet0(server, environment, metrics);
        final ContextRoutingHandler routingHandler = new ContextRoutingHandler(
                ImmutableMap.of(applicationContextPath, applicationHandler, adminContextPath, adminHandler));
        final Handler gzipHandler = buildGzipHandler(routingHandler);
        server.setHandler(addStatsHandler(addRequestLog(server, gzipHandler, environment.getName())));
    }
a helper method to facilitate the signature change in {@link AbstractServerFactory} in release 2.1, where
the 5th {@link AdminEnvironment} param is added.
dropwizard2/src/main/java/com/linecorp/armeria/dropwizard/ArmeriaServerFactory.java