Adapt classes with isolates

[AlexV525]

Request Statement

flutter/flutter#126520 (comment)

Recent versions of the Dart SDK have tightened the rules for which objects can be sent across isolates (see https://api.dart.dev/stable/3.0.0/dart-isolate/SendPort/send.html and dart-lang/sdk@67683c39)

Classes might cause unsendable issues when passing through isolates. Someone reported that MultipartFile is not sendable which fails the runtime.

Solution Brainstorm

Make those classes sendable, or figure out ways to handle them in isolates.

[AlexV525]

cc @kuhnroyal I saw a related request in OpenAPITools/openapi-generator#15516, could you check if we're capable to adapt similar changes as well?

[kuhnroyal]

The PR you linked involves types sent to an isolate due to generator code during encoding/decoding.
Here I don't believe this is something that dio is doing. The easy answer is, don't try to send complex types through a SendPort.

[AlexV525]

Great, thanks for the feedback!