Explicitly type Stream argument as List<int>

[mkustermann]

A breaking change (see [0]) will make utf8.encode() return the more precise Uint8List type (instead of the current List<int>).

In rare circumstances this can lead to changes in behavior, mainly when code relies on type inference, a different type got inferred and the code dependend on the type not being inferred a more precise type.

Here we explicitly use Stream<List<int>> instead of relying on type inference (which would infer Stream<Uint8List> in some cases after [0]). This is necessary as the stream transformer APIs cannot work with subtypes. Example of code that fails at runtime:

  import 'dart:typed_data';
  import 'dart:convert';

  void main() {
    Stream<Uint8List> stream = Stream.fromIterable([]);
    Stream<List<int>> stream2 = stream;
    stream2.transform(utf8.decoder);
         //  ^^^ Will throw due to Utf8Decoder not being subtype of
         //      StreamTransformer<Uint8List, String>.
  }

[0] dart-lang/sdk#52801

[mkustermann]

Thank you for the quick review & publish of package, @nex3 !