toJson method Null safety

Implementation

Map<String, Object?> toJson() {
  return {
    'pairingCode': pairingCode,
    'paired': paired,
    'name': name,
    'userID': userID,
    'lastUpdated': Timestamp.fromDate(lastUpdated),
    'screenToken': screenToken,
    'width': width,
    'height': height,
  };
}