private static int ensureValidPort(int port) {
        checkArgument(port >= 0 && port <= 65535,
                      "port: %s (expected: 0[arbitrary port] or 1-65535)", port);
        return port;
    }
Creates a new factory instance with the specified {@link ConfigurableListableBeanFactory}.
spring/boot3-webflux-autoconfigure/src/main/java/com/linecorp/armeria/spring/web/reactive/ArmeriaReactiveWebServerFactory.java