Server-Sent-Events (SSE) and HTTPS

I have a spring-boot backend and wanted to create a SSE endpoint, sample:

@CrossOrigin(origins = "http://localhost:4200") // Angular Dev-Server@GetMapping(path = "/stream-flux", produces = MediaType.TEXT_EVENT_STREAM_VALUE)public Flux<String> streamFlux() {    return Flux.interval(Duration.ofSeconds(1))            .map(sequence -> "data: Flux - " + LocalTime.now().toString() +"\n\n")            .doOnSubscribe(subscription -> {                System.out.println("SSE-Stream started.");            })            .doOnNext(value -> {                System.out.println("SSE-Value sent: " + value);            })            .doOnError(error -> {                System.out.println("SSE-Error: " + error.getMessage());            })            .doOnComplete(() -> {                System.out.println("SSE-Stream complete.");            });                }

Now, this example works perfect with an http-call (and the respective spring-server settings), tested with CURL.

curl -v http://localhost:8080/stream-flux

But when I wanted to switch to https (of course with the right spring-boot server settings)

tested with the following call:

curl -k -v https://localhost:<ssl-port>/stream-flux

The values from the event doesn't come at all with https.I am using a self-signed certificate.

And the CURL-answer is confusing to me:

* schannel: remote party requests renegotiation* schannel: renegotiating SSL/TLS connection* schannel: SSL/TLS connection renegotiated* Request completely sent off

Any approach to tackling this issue is highly appreciated.