anchor.diff:  // Use of this source code is governed by a BSD-style license that can be
   // found in the LICENSE file.
   
  -// @dart=2.9
  +// ignore_for_file: import_of_legacy_library_into_null_safe
   
   import 'package:flutter/material.dart';
   
  
positive.code:           totalHeight,
          ),
          _minSizes = modifyMinSizesToIncludeFirstHeader(minSizes, headers),
          super(key: key) {
      if (minSizes != null) {
        assert(minSizes.length == children.length);
      }
    }
  
    /// The headers that will be laid out above each corresponding child in
    /// [children].
  
negative.code: 
  class FlexSplitColumn extends StatelessWidget {
    FlexSplitColumn({
      Key? key,
      required this.totalHeight,
      required this.headers,
      required List<Widget> children,
      required List<double> initialFractions,
      required List<double> minSizes,
    })  : assert(children.length >= 2),
          assert(initialFractions.length >= 2),
          assert(children.length == initialFractions.length),
          assert(minSizes.length == children.length),
          _children = buildChildrenWithFirstHeader(children, headers),
          _initialFractions = modifyInitialFractionsToIncludeFirstHeader(
            initialFractions,
  