anchor.diff:    String toString() => '$runtimeType(asset: ${assetUri.path}, weight; $weight, style: $style)';
   }
   
  -Future<dynamic> _loadFlutterManifest(String manifestPath) async {
  -  if (manifestPath == null || !fs.isFileSync(manifestPath))
  -    return null;
  -  final String manifestDescriptor = await fs.file(manifestPath).readAsString();
  -  return loadYaml(manifestDescriptor);
  -}
  -
   Future<bool> _validate(Object manifest) async {
     final String schemaPath = fs.path.join(
       fs.path.absolute(Cache.flutterRoot), 'packages', 'flutter_tools', 'schema',
  
positive.code: import 'dart:async';
  
  import 'package:json_schema/json_schema.dart';
  import 'package:yaml/yaml.dart';
  
  import 'base/file_system.dart';
  
negative.code: class FlutterManifest {
    FlutterManifest._();
  
    /// Returns null on invalid manifest. Returns empty manifest on missing file.
    static Future<FlutterManifest> createFromPath(String path) async {
      if (path == null || !fs.isFileSync(path))
        return _createFromYaml(null);
      final String manifest = await fs.file(path).readAsString();
      return createFromString(manifest);
    }
  
    /// Returns null on missing or invalid manifest
    @visibleForTesting
    static Future<FlutterManifest> createFromString(String manifest) async {
      return _createFromYaml(loadYaml(manifest));
    }
  