toMap method

@override MutableMapping toMap()

Converts the wrapper's state to a structured Map (matches the format defined in this class).

Core logic:

• Serializes the data property (TransportableData) into the "data" field of the Map
• Subclasses may override this method to implement lazy serialization for other properties (e.g., defer encoding large file data until this method is called)

Returns: Serialized Map containing the file metadata and serialized data

Implementation

@override
MutableMapping toMap() {
  // serialize 'data'
  var ted = _attachment;
  if (ted != null && !containsKey('data')) {
    _map['data'] = ted.serialize();
  }
  // serialize 'key'
  var pwd = _password;
  if (pwd != null && !containsKey('key')) {
    _map['key'] = pwd.toMap();
  }
  // OK
  return _map;
}