fixed tests

packages/stream_chat/lib/src/core/api/message_api.dart

@@ -85,9 +85,11 @@ class MessageApi {
   }) async {
     final response = await _client.delete(
       '/messages/$messageId',
-      queryParameters: {
-        if (hard != null) 'hard': hard,
-      },
+      queryParameters: hard != null
+          ? {
+              'hard': hard,
+            }
+          : null,
     );
     return EmptyResponse.fromJson(response.data);
   }

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

@@ -8,7 +8,7 @@ part 'read.g.dart';
 @JsonSerializable()
 class Read extends Equatable {
   /// Constructor used for json serialization
-  Read({
+  const Read({
     required this.lastRead,
     required this.user,
     this.unreadMessages = 0,