Spring WebClient perform https call

Question

Does anyone know how to configure WebClient in order to make an HTTPS endpoint?

My config looks like that:

    @Bean
    @NonNull
    public WebClient webClient() throws SSLException {
        final SslContext context = SslContextBuilder.forClient()
                .trustManager(InsecureTrustManagerFactory.INSTANCE)
                .build();

        final HttpClient httpClient = HttpClient.create().secure(t -> t.sslContext(context));

        return WebClient
                .builder()
                .exchangeStrategies(ExchangeStrategies.builder()
                        .codecs(configurer -> configurer.defaultCodecs().maxInMemorySize(16 * 1024 * 1024))
                        .build())
                .defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
                .clientConnector(new ReactorClientHttpConnector(httpClient))
                .build();
    }

here is the method witch hits HTTPS endpoint

    @Nullable
    public AccessToken getAccessToken() {
        return webClient
                .post()
                .uri(uriBuilder -> uriBuilder.path(authUrl)
                        .queryParam("username", username)
                        .queryParam("password", password)
                        .queryParam("client_id", clientId)
                        .queryParam("client_secret", clientSecret)
                        .queryParam("grant_type", "password")
                        .build())
                .header("Content-Type", MediaType.APPLICATION_JSON_VALUE)
                .exchange()
                .flatMap(response -> {
                    //Error handling
                    if (response.statusCode().isError()) {
                        logger.error("error occured while authentication: {}", response.statusCode());
                        return response.createException().flatMap(Mono::error);
                    }
                    return response.bodyToMono(AccessToken.class);
                })
                .subscribeOn(Schedulers.elastic())
                .block();
    }

and that's my reponse, unfortunately I'm not allowed to show all the details cause there are secured data. So I've checked everything like URL, parameters, all looks fine. Also if do the same with restTemaple it works.

Caused by: java.net.UnknownHostException: https:
    at java.base/java.net.InetAddress$CachedAddresses.get(InetAddress.java:798)
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
    |_ checkpoint ⇢ Request to POST https:/<here goes secured endpoint with query parameters>