migrate ui

packages/stream_chat_flutter/lib/src/connection_status_builder.dart

@@ -11,26 +11,25 @@ import 'stream_chat.dart';
 class ConnectionStatusBuilder extends StatelessWidget {
   /// Creates a new ConnectionStatusBuilder
   const ConnectionStatusBuilder({
-    Key key,
-    @required this.statusBuilder,
+    Key? key,
+    required this.statusBuilder,
     this.initialStatus = ConnectionStatus.disconnected,
     this.connectionStatusStream,
     this.errorBuilder,
     this.loadingBuilder,
-  })  : assert(statusBuilder != null),
-        super(key: key);
+  }) : super(key: key);
 
   /// The connection status that will be used to create the initial snapshot.
   final ConnectionStatus initialStatus;
 
   /// The asynchronous computation to which this builder is currently connected.
-  final Stream<ConnectionStatus> connectionStatusStream;
+  final Stream<ConnectionStatus>? connectionStatusStream;
 
   /// The builder that will be used in case of error
-  final Widget Function(BuildContext context, Object error) errorBuilder;
+  final Widget Function(BuildContext context, Object? error)? errorBuilder;
 
   /// The builder that will be used in case of loading
-  final WidgetBuilder loadingBuilder;
+  final WidgetBuilder? loadingBuilder;
 
   /// The builder that will be used in case of data
   final Widget Function(BuildContext context, ConnectionStatus status)
@@ -46,15 +45,15 @@ class ConnectionStatusBuilder extends StatelessWidget {
       builder: (context, snapshot) {
         if (snapshot.hasError) {
           if (errorBuilder != null) {
-            return errorBuilder(context, snapshot.error);
+            return errorBuilder!(context, snapshot.error);
           }
           return Offstage();
         }
         if (!snapshot.hasData) {
-          if (loadingBuilder != null) return loadingBuilder(context);
+          if (loadingBuilder != null) return loadingBuilder!(context);
           return Offstage();
         }
-        return statusBuilder(context, snapshot.data);
+        return statusBuilder(context, snapshot.data!);
       },
     );
   }