@Override
    public X509Certificate getRoleCertificate(AthenzRole role, Pkcs10Csr csr, Duration expiry) {
        RoleCertificateRequestEntity requestEntity = new RoleCertificateRequestEntity(csr, expiry);
        URI uri = ztsUrl.resolve("rolecert");
        HttpUriRequest request = RequestBuilder.post(uri)
                .setEntity(toJsonStringEntity(requestEntity))
                .build();
        return execute(request, response -> {
            RoleCertificateResponseEntity responseEntity = readEntity(response, RoleCertificateResponseEntity.class);
            return responseEntity.certificate;
        });
    }
Default implementation of {@link ZtsClient}

@author bjorncs
@author mortent
vespa-athenz/src/main/java/com/yahoo/vespa/athenz/client/zts/DefaultZtsClient.java