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runtime/observatory/lib/src/models/objects/inbound_references.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of models;
 
 abstract class InboundReferences {
   Iterable<InboundReference> get elements;
 }
 
 abstract class InboundReference {
   ObjectRef get source;
+
   /// [optional]
   ObjectRef get parentField;
+
   /// [optional]
   int get parentListIndex;
+
   /// [optional]
   int get parentWordOffset;
 }