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)),
};