make language nullable

packages/stream_chat/lib/src/core/models/own_user.dart

@@ -27,7 +27,7 @@ class OwnUser extends User {
     Map<String, Object?> extraData = const {},
     bool banned = false,
     List<String> teams = const [],
-    String language = 'en',
+    String? language,
   }) : super(
           id: id,
           role: role,

packages/stream_chat/lib/src/core/models/own_user.g.dart

@@ -39,6 +39,6 @@ OwnUser _$OwnUserFromJson(Map<String, dynamic> json) {
     teams:
         (json['teams'] as List<dynamic>?)?.map((e) => e as String).toList() ??
             [],
-    language: json['language'] as String? ?? 'en',
+    language: json['language'] as String,
   );
 }

packages/stream_chat/lib/src/core/models/user.dart

@@ -18,7 +18,7 @@ class User extends Equatable {
     this.extraData = const {},
     this.banned = false,
     this.teams = const [],
-    this.language = 'en',
+    this.language,
   })  : createdAt = createdAt ?? DateTime.now(),
         updatedAt = updatedAt ?? DateTime.now();
 
@@ -87,12 +87,8 @@ class User extends Equatable {
   /// The language this user prefers.
   ///
   /// Defaults to 'en'.
-  @JsonKey(
-    includeIfNull: false,
-    toJson: Serializer.readOnly,
-    defaultValue: 'en',
-  )
-  final String language;
+  @JsonKey(includeIfNull: false)
+  final String? language;
 
   /// Shortcut for user name
   String get name {

packages/stream_chat/lib/src/core/models/user.g.dart

@@ -25,7 +25,7 @@ User _$UserFromJson(Map<String, dynamic> json) {
     teams:
         (json['teams'] as List<dynamic>?)?.map((e) => e as String).toList() ??
             [],
-    language: json['language'] as String? ?? 'en',
+    language: json['language'] as String?,
   );
 }
 
@@ -48,6 +48,6 @@ Map<String, dynamic> _$UserToJson(User instance) {
   writeNotNull('online', readonly(instance.online));
   writeNotNull('banned', readonly(instance.banned));
   val['extra_data'] = instance.extraData;
-  writeNotNull('language', readonly(instance.language));
+  writeNotNull('language', instance.language);
   return val;
 }