toJson method
Implementation
Map<String, Object?> toJson() {
final data = <String, Object?>{};
if (type != null) data['type'] = type;
if (sender != null) data['sender'] = sender;
if (content != null) data['content'] = content;
if (recipient != null) data['recipient'] = recipient;
if (recipientKeys != null) data['recipient_keys'] = recipientKeys;
if (keys != null) data['keys'] = keys;
return data;
}