toJson method Null safety
Implementation
Map<String, dynamic> toJson() => {
"content": List<dynamic>.from(content!.map((x) => x)),
"code": List<dynamic>.from(code!.map((x) => x)),
"keys": keys!.toJson(),
"ledger": ledger!.toJson(),
"recipients": List<dynamic>.from(recipients!.map((x) => x)),
};