toMap method
Implementation
Map<String, dynamic> toMap() {
return <String, dynamic>{
'id': id,
'title': title,
'content': content,
'fireTime': fireTime?.millisecondsSinceEpoch,
'buildId': buildId,
'extra': extra,
'badge': badge,
'soundName': soundName,
'subtitle': subtitle
}..removeWhere((key, value) => value == null);
}