The X.509 Certificates that are used to encrypt communications in an Elasticsearch cluster using the security().getSslCertificates() method:

GetSslCertificatesResponse response = client.security().getSslCertificates(RequestOptions.DEFAULT);

The returned GetSslCertificatesResponse contains a single field, certificates. This field, accessed with getCertificates returns a List of CertificateInfo objects containing the information for all the certificates used.

List<CertificateInfo> certificates = response.getCertificates(); 

This request can be executed asynchronously using the security().getSslCertificatesAsync() method:

client.security().getSslCertificatesAsync(RequestOptions.DEFAULT, listener); 

The asynchronous method does not block and returns immediately. Once the request has completed the ActionListener is called back using the onResponse method if the execution successfully completed or using the onFailure method if it failed.

A typical listener for a GetSslCertificatesResponse looks like:

ActionListener<GetSslCertificatesResponse> listener = new ActionListener<GetSslCertificatesResponse>() {
    @Override
    public void onResponse(GetSslCertificatesResponse getSslCertificatesResponse) {
        
    }

    @Override
    public void onFailure(Exception e) {
        
    }
};