fix: http download fail (#61)

ui/flutter/lib/api/model/options.dart

@@ -2,11 +2,12 @@ import 'package:json_annotation/json_annotation.dart';
 
 part 'options.g.dart';
 
-@JsonSerializable()
+@JsonSerializable(explicitToJson: true, genericArgumentFactories: true)
 class Options {
   String name;
   String path;
   List<int> selectFiles;
+  Map<String, dynamic>? extra;
 
   Options({
     required this.name,
@@ -19,3 +20,14 @@ class Options {
 
   Map<String, dynamic> toJson() => _$OptionsToJson(this);
 }
+
+@JsonSerializable()
+class OptsExtraHttp {
+  int connections = 0;
+
+  OptsExtraHttp();
+
+  factory OptsExtraHttp.fromJson(Map<String, dynamic> json) =>
+      _$OptsExtraHttpFromJson(json);
+  Map<String, dynamic> toJson() => _$OptsExtraHttpToJson(this);
+}