fix json serialization nnbd

packages/stream_chat/lib/src/db/chat_persistence_client.dart

@@ -237,7 +237,7 @@ abstract class ChatPersistenceClient {
 
     final updateMembersFuture = channelStates.map((it) {
       final cid = it.channel!.cid;
-      final members = it.members.where((it) => it != null);
+      final members = it.members;
       return updateMembers(cid, members.toList(growable: false));
     }).toList(growable: false);
 

packages/stream_chat/lib/src/models/attachment.dart

@@ -49,12 +49,12 @@ class Attachment extends Equatable {
   /// Create a new instance from a json
   factory Attachment.fromJson(Map<String, dynamic> json) =>
       _$AttachmentFromJson(
-          Serialization.moveToExtraDataFromRoot(json, topLevelFields)!);
+          Serialization.moveToExtraDataFromRoot(json, topLevelFields));
 
   /// Create a new instance from a db data
   factory Attachment.fromData(Map<String, dynamic> json) =>
       _$AttachmentFromJson(Serialization.moveToExtraDataFromRoot(
-          json, topLevelFields + dbSpecificTopLevelFields)!);
+          json, topLevelFields + dbSpecificTopLevelFields));
 
   ///The attachment type based on the URL resource. This can be: audio,
   ///image or video

packages/stream_chat/lib/src/models/channel_model.dart

@@ -28,9 +28,9 @@ class ChannelModel {
         updatedAt = updatedAt ?? DateTime.now();
 
   /// Create a new instance from a json
-  factory ChannelModel.fromJson(Map<String, dynamic>? json) =>
+  factory ChannelModel.fromJson(Map<String, dynamic> json) =>
       _$ChannelModelFromJson(
-          Serialization.moveToExtraDataFromRoot(json, topLevelFields)!);
+          Serialization.moveToExtraDataFromRoot(json, topLevelFields));
 
   /// The id of this channel
   final String? id;

packages/stream_chat/lib/src/models/event.dart

@@ -31,11 +31,11 @@ class Event {
   }) : isLocal = true;
 
   /// Create a new instance from a json
-  factory Event.fromJson(Map<String, dynamic>? json) =>
+  factory Event.fromJson(Map<String, dynamic> json) =>
       _$EventFromJson(Serialization.moveToExtraDataFromRoot(
         json,
         topLevelFields,
-      )!)
+      ))
         ..isLocal = false;
 
   /// The type of the event
@@ -197,11 +197,11 @@ class EventChannel extends ChannelModel {
         );
 
   /// Create a new instance from a json
-  factory EventChannel.fromJson(Map<String, dynamic>? json) =>
+  factory EventChannel.fromJson(Map<String, dynamic> json) =>
       _$EventChannelFromJson(Serialization.moveToExtraDataFromRoot(
         json,
         topLevelFields,
-      )!);
+      ));
 
   /// A paginated list of channel members
   final List<Member>? members;

packages/stream_chat/lib/src/models/message.dart

@@ -80,8 +80,8 @@ class Message extends Equatable {
         updatedAt = updatedAt ?? DateTime.now();
 
   /// Create a new instance from a json
-  factory Message.fromJson(Map<String, dynamic>? json) => _$MessageFromJson(
-      Serialization.moveToExtraDataFromRoot(json, topLevelFields)!);
+  factory Message.fromJson(Map<String, dynamic> json) => _$MessageFromJson(
+      Serialization.moveToExtraDataFromRoot(json, topLevelFields));
 
   /// The message ID. This is either created by Stream or set client side when
   /// the message is added.
@@ -389,9 +389,9 @@ class TranslatedMessage extends Message {
   TranslatedMessage(this.i18n) : super();
 
   /// Create a new instance from a json
-  factory TranslatedMessage.fromJson(Map<String, dynamic>? json) =>
+  factory TranslatedMessage.fromJson(Map<String, dynamic> json) =>
       _$TranslatedMessageFromJson(
-        Serialization.moveToExtraDataFromRoot(json, topLevelFields)!,
+        Serialization.moveToExtraDataFromRoot(json, topLevelFields),
       );
 
   /// A Map of

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

@@ -37,8 +37,8 @@ class OwnUser extends User {
         );
 
   /// Create a new instance from a json
-  factory OwnUser.fromJson(Map<String, dynamic>? json) => _$OwnUserFromJson(
-      Serialization.moveToExtraDataFromRoot(json, topLevelFields)!);
+  factory OwnUser.fromJson(Map<String, dynamic> json) => _$OwnUserFromJson(
+      Serialization.moveToExtraDataFromRoot(json, topLevelFields));
 
   /// List of user devices
   @JsonKey(

packages/stream_chat/lib/src/models/reaction.dart

@@ -19,8 +19,11 @@ class Reaction {
   }) : userId = userId ?? user.id;
 
   /// Create a new instance from a json
-  factory Reaction.fromJson(Map<String, dynamic>? json) => _$ReactionFromJson(
-      Serialization.moveToExtraDataFromRoot(json, topLevelFields)!);
+  factory Reaction.fromJson(Map<String, dynamic> json) =>
+      _$ReactionFromJson(Serialization.moveToExtraDataFromRoot(
+        json,
+        topLevelFields,
+      ));
 
   /// The messageId to which the reaction belongs
   final String? messageId;

packages/stream_chat/lib/src/models/serialization.dart

@@ -14,12 +14,10 @@ class Serialization {
       users?.map((u) => u.id).toList();
 
   /// Takes unknown json keys and puts them in the `extra_data` key
-  static Map<String, dynamic>? moveToExtraDataFromRoot(
-    Map<String, dynamic>? json,
+  static Map<String, dynamic> moveToExtraDataFromRoot(
+    Map<String, dynamic> json,
     List<String> topLevelFields,
   ) {
-    if (json == null) return null;
-
     final jsonClone = Map<String, dynamic>.from(json);
 
     final extraDataMap = Map<String, dynamic>.from(json)

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

@@ -21,8 +21,8 @@ class User {
         updatedAt = updatedAt ?? DateTime.now();
 
   /// Create a new instance from a json
-  factory User.fromJson(Map<String, dynamic>? json) => _$UserFromJson(
-      Serialization.moveToExtraDataFromRoot(json, topLevelFields)!);
+  factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(
+      Serialization.moveToExtraDataFromRoot(json, topLevelFields));
 
   /// Use this named constructor to create a new user instance
   User.init(