@Override
  public JsonObjectBuilder getJsonObjectBuilder() {
    return super.getJsonObjectBuilder()
      .add("fingerprint", this.fingerprint)
      .add("fingerprintAlgorithm", this.fingerprintAlgorithm)
      .add("base64Certificate", this.base64Certificate)
      .add("issuerCertificateId", this.issuerCertificateId);
  }
RTCCertificateStats, with attributes fingerprint,
fingerprintAlgorithm, base64Certificate, issuerCertificateId
KITE-Framework/src/main/java/org/webrtc/kite/stats/rtc/RTCCertificateStats.java