@Override
    public String getId() {
        if (this.certificate != null) {
            return CertUtils.toString(this.certificate);
        }
        if (this.certificates.length > 0) {
            return CertUtils.toString(this.certificates[0]);
        }
        return UNKNOWN_ID;
    }
The certificate that we actually use.
support/cas-server-support-x509-core/src/main/java/org/apereo/cas/adaptors/x509/authentication/principal/X509CertificateCredential.java