public class Server extends VerticleBase { public Future<?> start() { return vertx.createHttpServer() .requestHandler(req -> req.response() .putHeader("content-type", "text/plain") .end("Hello from Vert.x!") ) .listen(8080); } } class Server : VerticleBase() { override fun start(): Future<*> { return vertx.createHttpServer() .requestHandler { req -> req.response() .putHeader("content-type", "text/