anchor.diff:  /// Class that maintains a mapping from included/excluded paths to a set of
   /// folders that should correspond to analysis contexts.
   class ContextManagerImpl implements ContextManager {
  -  /// The [ResourceProvider] using which paths are converted into [Resource]s.
  -  final ResourceProvider resourceProvider;
  +  /// The [OverlayResourceProvider] used to check for the existence of overlays
  +  /// and to convert paths into [Resource].
  +  final OverlayResourceProvider resourceProvider;
   
     /// The manager used to access the SDK that should be associated with a
     /// particular context.
  
positive.code:     }
  
      var collection = _collection;
      if (collection != null && file_paths.isDart(pathContext, path)) {
        for (var analysisContext in collection.contexts) {
          switch (type) {
            case ChangeType.ADD:
  
negative.code: import 'package:analyzer/dart/analysis/features.dart';
  import 'package:analyzer/error/listener.dart';
  import 'package:analyzer/file_system/file_system.dart';
  import 'package:analyzer/file_system/overlay_file_system.dart';
  import 'package:analyzer/instrumentation/instrumentation.dart';
  import 'package:analyzer/src/dart/analysis/analysis_context_collection.dart';
  import 'package:analyzer/src/dart/analysis/byte_store.dart';
  