putData not working but not setting the metadata

[MukalDadhwal]

putData() function when called on storage reference along by passing settablemetadata uploads the data but with no metadata.
Here is the code

UploadTask task = storage
      .refFromURL('location_url')
      .child('${map['id']}.mp4')
      .putData(uint8List, metadata);

Also no errors are being generated as I am also checking it afterwards

task.snapshotEvents.listen((event) {
    if (event.state == TaskState.error) {
      print('Some serious error is coming');
    } else {
      print('It works');
    }
  });

It works gets printed.
The code works on a flutter app but not inside the script.

[ciceromsjr]

The problem is on asMap method of SettableMetadata class.

WRONG:

Map<String, dynamic> asMap() => {
'cacheControl': cacheControl,
'contentDisposition': contentDisposition,
'contentEncoding': contentEncoding,
'contentLanguage': contentLanguage,
'contentType': contentType,
'customMetadata': customMetadata, // <<<<<. WRONG
};

FIX:

Map<String, dynamic> asMap() => {
'cacheControl': cacheControl,
'contentDisposition': contentDisposition,
'contentEncoding': contentEncoding,
'contentLanguage': contentLanguage,
'contentType': contentType,
'metadata': customMetadata, // <<<<<. RIGHT!
};