class WebServices extends CMSPlugin implements SubscriberInterface {

    public static function getSubscribedEvents(): array {
        return [
            'onBeforeApiRoute' => 'onBeforeApiRoute',
        ];
    }
    
    public function onBeforeApiRoute(Event $event) : void {
        [$router] = array_values($event->getArguments());

        $defaults = [
            'component'  => 'com_example',
            'public' => true,
            'format' => ['application/json'] // Does not work on Joomla 4 (works on Joomla 5)
        ];

        $routes = [
            new Route(['GET'], 'v1/example/configuration', 'configuration.get', [], $defaults),
        ];

        $router->addRoutes($routes);
    }
}