finished implementation

packages/pluggable_transports_proxy/lib/src/data/models/moat.dart

@@ -83,13 +83,19 @@ class Setting {
 
 @JsonSerializable()
 class Bridge {
-  final String type;
+  @JsonKey(toJson: _transportToJson, fromJson: _transportFromJson)
+  final TransportType type;
   final String source;
   @JsonKey(name: 'bridge_strings')
   final List<String>? bridges;
 
   const Bridge({required this.type, required this.source, this.bridges});
 
+  static String _transportToJson(TransportType transport) => transport.value;
+
+  static TransportType _transportFromJson(dynamic json) =>
+      TransportType.fromString(json as String)!;
+
   factory Bridge.fromJson(Map<String, dynamic> json) => _$BridgeFromJson(json);
 
   Map<String, dynamic> toJson() => _$BridgeToJson(this);

packages/pluggable_transports_proxy/lib/src/data/models/moat.g.dart

@@ -50,7 +50,7 @@ Map<String, dynamic> _$SettingToJson(Setting instance) => <String, dynamic>{
 };
 
 Bridge _$BridgeFromJson(Map<String, dynamic> json) => Bridge(
-  type: json['type'] as String,
+  type: Bridge._transportFromJson(json['type']),
   source: json['source'] as String,
   bridges: (json['bridge_strings'] as List<dynamic>?)
       ?.map((e) => e as String)
@@ -58,7 +58,7 @@ Bridge _$BridgeFromJson(Map<String, dynamic> json) => Bridge(
 );
 
 Map<String, dynamic> _$BridgeToJson(Bridge instance) => <String, dynamic>{
-  'type': instance.type,
+  'type': Bridge._transportToJson(instance.type),
   'source': instance.source,
   'bridge_strings': instance.bridges,
 };