anchor.diff:      }
   
       // call the build UI callback.
  -    if (buildCallback != null) {
  -      buildCallback(
  -        referenceName,
  -        owningAllocator,
  -        owningAllocatorIsAbstract,
  -      );
  -    }
  +    buildCallback(
  +      referenceName,
  +      owningAllocator,
  +      owningAllocatorIsAbstract,
  +    );
     }
   }
   
  
positive.code:   }
  
    static InboundReference parse(Map<String, dynamic> json) {
      return json == null ? null : InboundReference._fromJson(json);
    }
  
    dynamic parentField;
  
    int parentListIndex;
  
    int parentWordOffset;
  
    bool get isFieldRef => parentField.runtimeType == FieldRef;
  
    FieldRef get fieldRef => isFieldRef ? parentField as FieldRef : null;
  
    bool get isClassRef => parentField.runtimeType == ClassRef;
  
    ClassRef get classRef => isFieldRef ? parentField as ClassRef : null;
  
    bool get isFuncRef => parentField.runtimeType == FuncRef;
  
    FuncRef get funcRef => isFuncRef ? parentField as FuncRef : null;
  
    bool get isNullVal => parentField.runtimeType == NullVal;
  
    bool get isNullValRef => parentField.runtimeType == NullValRef;
  
    NullVal get nullVal => isInstanceRef ? parentField as NullVal : null;
  
    bool get isInstance => parentField.runtimeType == Instance;
  
    Instance get instance => isInstance ? parentField as Instance : null;
  
    bool get isInstanceRef => parentField.runtimeType == InstanceRef;
  
    InstanceRef get instanceRef =>
        isInstanceRef ? parentField as InstanceRef : null;
  
    bool get isLibrary => parentField.runtimeType == Library;
  
    bool get isLibraryRef => parentField.runtimeType == LibraryRef;
  
    Library get library => isLibrary ? parentField as Library : null;
  
    bool get isObj => parentField.runtimeType == Obj;
  
    bool get isObjRef => parentField.runtimeType == ObjRef;
  
    Obj get obj => isObj ? parentField as Obj : null;
  
    bool get isSentinel => parentField.runtimeType == Sentinel;
  }
  
  typedef BuildInboundEntry = void Function(
    String referenceName,
    /* Field that owns reference to allocated memory */
    String owningAllocator,
    /* Parent class that allocated memory. */
    bool owningAllocatorIsAbstract,
    /* is owning class abstract */
  );
  
  ClassHeapDetailStats _searchClass(
    List<ClassHeapDetailStats> allClasses,
    String className,
  ) =>
      allClasses.firstWhere((dynamic stat) => stat.classRef.name == className,
          orElse: () => null);
  
  // Compute the inboundRefs, who allocated the class/which field owns the ref.
  void computeInboundRefs(
  
negative.code: // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  import 'package:collection/collection.dart' show IterableExtension;
  import 'package:devtools_shared/devtools_shared.dart';
  import 'package:vm_service/vm_service.dart';
  
  