anchor.diff:    }
   }
   
  -// This class exists to work around https://github.com/dart-lang/sdk/issues/31543
  -abstract class _RenderSliverScrollingPersistentHeader extends RenderSliverScrollingPersistentHeader { }
  -
  -class _RenderSliverScrollingPersistentHeaderForWidgets extends _RenderSliverScrollingPersistentHeader
  +class _RenderSliverScrollingPersistentHeaderForWidgets extends RenderSliverScrollingPersistentHeader
     with _RenderSliverPersistentHeaderForWidgetsMixin { }
   
   class _SliverPinnedPersistentHeader extends _SliverPersistentHeaderRenderObjectWidget {
  
positive.code:   }
  }
  
  // This class exists to work around https://github.com/dart-lang/sdk/issues/31543
  abstract class _RenderSliverPinnedPersistentHeader extends RenderSliverPinnedPersistentHeader { }
  
  class _RenderSliverPinnedPersistentHeaderForWidgets extends _RenderSliverPinnedPersistentHeader with _RenderSliverPersistentHeaderForWidgetsMixin { }
  
  class _SliverFloatingPersistentHeader extends _SliverPersistentHeaderRenderObjectWidget {
    const _SliverFloatingPersistentHeader({
  
negative.code: 
    @override
    _RenderSliverPersistentHeaderForWidgetsMixin createRenderObject(BuildContext context) {
      return _RenderSliverFloatingPersistentHeaderForWidgets(snapConfiguration: delegate.snapConfiguration);
    }
  
    @override
  