图像左下角图标 reviewed by baka

lib/components/picture_components.dart

@@ -87,7 +87,7 @@ class ContentImage extends StatelessWidget implements FWidget {
     this.onDoubleTap,
     this.onTap,
     this.isSelectStutas = false,
-    this.application = '',
+    this.application,
   }) : super(key: key);
 
   @override