thirdpartyProxy.java

@Get("/test")
public HttpResponse getTest(RequestContext ctx) {
    CompletableFuture<HttpResponse> future = new CompletableFuture<>();
    WebClient client = WebClient.of("https://icanhazdadjoke.com");
    HttpResponse response = client.execute(RequestHeaders.of(HttpMethod.GET, "/", HttpHeaderNames.ACCEPT, HttpHeaderValues.APPLICATION_JSON));
    response.aggregate().thenAccept(aggregatedRes -> {
        try (SafeCloseable ignored = ctx.push()) {
            AggregatedHttpResponse res = ...  // do something with `aggregatedRes`
            future.complete(res.toHttpResponse());
        }
    });
    return HttpResponse.from(future);
}