toJson method
Implementation
core.Map<core.String, core.dynamic> toJson() => {
      if (keyId != null) 'keyId': keyId!,
      if (publicKeyPem != null) 'publicKeyPem': publicKeyPem!,
      if (signatureAlgorithm != null)
        'signatureAlgorithm': signatureAlgorithm!,
    };