Support CompletableFuture as a response type of a RequestFilter method

[sdelamo]

I think it would be good to support CompletableFuture<HttpResponse> as a return type of @RequestFilter method..

[sdelamo]

thoughts @yawkat @dstepanov ?

[yawkat]

sure why not

[dstepanov]

I think it's supported

[yawkat]

Another undocumented feature? haha

[sdelamo]

it does not work. I tried in micronaut-projects/micronaut-security#1826 and it does not work.

[sdelamo]

well, it works with CompletableFuture<@Nullable HttpResponse<?>> . It does not work with CompletableFuture< HttpResponse<?>>. That it is not documented.

[sdelamo]

I created a PR to document it #11285