upgrade reorderable_list

com.unity.uiwidgets/Runtime/material/reorderable_list.cs

 
     public class ReorderableListView : StatefulWidget {
         public ReorderableListView(
+            Key key = null,
+            ScrollController scrollController = null,
-        ) {
+        ) : base(key: key) {
             D.assert(onReorder != null);
             D.assert(children != null);
             D.assert(
             this.header = header;
             this.children = children;
+            this.scrollController = scrollController;
             this.scrollDirection = scrollDirection;
             this.padding = padding;
             this.onReorder = onReorder;
         public readonly List<Widget> children;
 
         public readonly Axis scrollDirection;
+        
+        public readonly ScrollController scrollController;
 
         public readonly EdgeInsets padding;
 
                     return new _ReorderableListContent(
                         header: widget.header,
                         children: widget.children,
+                        scrollController: widget.scrollController,
                         scrollDirection: widget.scrollDirection,
                         onReorder: widget.onReorder,
                         padding: widget.padding,
         public _ReorderableListContent(
             Widget header,
             List<Widget> children,
+            ScrollController scrollController,
             Axis scrollDirection,
             EdgeInsets padding,
             ReorderCallback onReorder,
             this.children = children;
+            this.scrollController = scrollController;
             this.scrollDirection = scrollDirection;
             this.padding = padding;
             this.onReorder = onReorder;
         public readonly Widget header;
         public readonly List<Widget> children;
+        public readonly ScrollController scrollController;
         public readonly Axis scrollDirection;
         public readonly EdgeInsets padding;
         public readonly ReorderCallback onReorder;
         }
 
         public override void didChangeDependencies() {
-            _scrollController = PrimaryScrollController.of(context) ?? new ScrollController();
+            _scrollController = widget.scrollController ?? PrimaryScrollController.of(context) ?? new ScrollController();
             base.didChangeDependencies();
         }
 
             D.assert(material_.debugCheckHasMaterialLocalizations(context));
             return new LayoutBuilder(builder: (BuildContext _, BoxConstraints constraints) => {
                 List<Widget> wrappedChildren = new List<Widget> { };
-                if (widget.header != null) {
-                    wrappedChildren.Add(widget.header);
-                }
-
-                for (int i = 0; i < widget.children.Count; i += 1) {
-                    wrappedChildren.Add(_wrap(widget.children[i], i, constraints));
-                }
-
+                
                 Key endWidgetKey = Key.key("DraggableList - End Widget");
                 Widget finalDropArea;
                 switch (widget.scrollDirection) {
                 }
 
                 if (widget.reverse == true) {
-                    wrappedChildren.Insert(0, _wrap(
+                    wrappedChildren.Add(_wrap(
-                else {
+                if (widget.header != null) {
+                    wrappedChildren.Add(widget.header);
+                }
+                for (int i = 0; i < widget.children.Count; i += 1) {
+                    wrappedChildren.Add(_wrap(widget.children[i], i, constraints));
+                }
+
+                
+                if (widget.reverse != true) {
                     wrappedChildren.Add(_wrap(
                         finalDropArea, widget.children.Count,
                         constraints)