supported auto discovery of global Hudson-level Widgets

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@15668 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/Hudson.java

@@ -275,7 +275,7 @@ public final class Hudson extends Node implements ItemGroup<TopLevelItem>, Stapl
     /**
      * Widgets on Hudson.
      */
-    private transient final List<Widget> widgets = new CopyOnWriteArrayList<Widget>();
+    private transient final List<Widget> widgets = getExtensionList(Widget.class);
 
     private transient volatile DependencyGraph dependencyGraph;