Client certificate authentication Spring Boot - RestClient

Question

I'm trying to use new RestClient with client certificate authentication, however I'm getting access denied (however works with curl). My thought process was something along:

1. create KeyStore with key, cert and chain

private KeyStore getKeyStore() throws Exception{
        var cert = certificateRepository.findByFqdnEqualsIgnoreCase("cert.domain.org").orElseThrow();
        KeyStore keyStore = KeyStore.getInstance("JKS");
        keyStore.load(null, null);

        var decPass = aesCypherService.decodeByPassword(cert.getPassword(), iv);
        String privateKey = aesCypherService.decodeByPassword(cert.getDataPrivate(), decPass);

        var chain = new Certificate[1+cert.getChain().size()];

        chain[0] = SSLUtils.getCertificateFromString(aesCypherService.decodeByPassword(cert.getDataPublic(), decPass));

        var it = 1;
        for(var chainCerts : cert.getChain())
        {
            chain[it] = SSLUtils.getCertificateFromString(chainCerts.getDataPublic());
            it++;
        }


        keyStore.setKeyEntry("serviceurl.org", SSLUtils.getPrivateKeyFromString(privateKey), generatedPassword.toCharArray(), chain);

        return keyStore;
    }

2. create HttpClient using keystore as its ssl context

private HttpClient clientHttpRequestFactory() {

        SSLContext sslContext;
        try {
            sslContext = SSLContextBuilder
                    .create()
                    .loadKeyMaterial(getKeyStore(), generatedPassword.toCharArray())
                    .loadTrustMaterial(null, TrustAllStrategy.INSTANCE)
                    .build();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }

        SSLConnectionSocketFactory socketFactory = SSLConnectionSocketFactoryBuilder.create().setSslContext(sslContext).build();

        HttpClientConnectionManager connectionManager = PoolingHttpClientConnectionManagerBuilder.create()
                .setSSLSocketFactory(socketFactory)
                .build();


        return HttpClients.custom()
                .setConnectionManager(connectionManager)
                .setTargetAuthenticationStrategy(new DefaultAuthenticationStrategy())
                .build();
    }

3. create underlying RestTemplate

@Bean
    @Qualifier("customRestTemplate")
    public RestTemplate customRestTemplate() {
        RestTemplate restTemplate = new RestTemplateBuilder()
                .rootUri("https://serviceurl.org")
                .requestFactory(() -> new HttpComponentsClientHttpRequestFactory(clientHttpRequestFactory()))
                .build();

        return restTemplate;
    }

4. create RestClient (via predefined interface)

@Bean
    public MyRestClientImpl myRestClientImpl(@Qualifier("customRestTemplate") RestTemplate restTemplate)
    {
        var rc = RestClient.builder(restTemplate)
                .baseUrl("https://serviceurl.org")
                .build();
        HttpServiceProxyFactory factory = HttpServiceProxyFactory.builderFor(RestClientAdapter.create(rc)).build();
        return factory.createClient(MyRestClientImpl.class);
    }

Please is there any way to debug this easily? Or is there any mistake in my thought process / code?