use_modular_headers (#42204)

diff --git a/examples/hello_world/ios/Runner/GeneratedPluginRegistrant.h b/examples/hello_world/ios/Runner/GeneratedPluginRegistrant.h
index 3b700eb..ed9a5c6 100644
--- a/examples/hello_world/ios/Runner/GeneratedPluginRegistrant.h
+++ b/examples/hello_world/ios/Runner/GeneratedPluginRegistrant.h
@@ -7,8 +7,11 @@
 
 #import <Flutter/Flutter.h>
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface GeneratedPluginRegistrant : NSObject
 + (void)registerWithRegistry:(NSObject<FlutterPluginRegistry>*)registry;
 @end
 
+NS_ASSUME_NONNULL_END
 #endif /* GeneratedPluginRegistrant_h */