4.6.2.3.8. 要求オプションの新しいメソッド

client.request(HttpMethod.GET, 8080, "example.com", "/resource", ar -> {
  if (ar.succeeded()) {
    HttpClientRequest request = ar.result();
    request.putHeader("content-type", "application/json")
    request.send(new JsonObject().put("hello", "world"))
      .onSuccess(response -> {
      //
      }).onFailure(err -> {
      //
       });
     }
})