initialize method
Implementation
@override
Future<bool?> initialize(
    [String mediaId = "",
    String mediaSecret = "",
    String callbackTag = "",
    String childYN = ""]) async {
  final result =
      await methodChannel.invokeMethod<bool>('initialize', <String, dynamic>{
    "mediaId": mediaId,
    "mediaSecret": mediaSecret,
    "callbackTag": callbackTag,
    "childYN": childYN
  });
  return result;
}