anchor.diff:    /// Specifies whether the isolate was spawned by the VM or embedder for
     /// internal use. If `false`, this isolate is likely running user code.
     bool? isSystemIsolate;
  +
  +  /// The id of the isolate group that this isolate belongs to.
  +  String? isolateGroupId;
   
     /// The list of isolate flags provided to this isolate. See Dart_IsolateFlags
     /// in dart_api.h for the list of accepted isolate flags.
  
positive.code:     this.number,
      this.name,
      this.isSystemIsolate,
      this.isolateFlags,
      this.startTime,
      this.runnable,
  
negative.code:   bool operator ==(Object other) => other is IsolateRef && id == other.id;
  
    String toString() => '[IsolateRef ' //
        'id: ${id}, number: ${number}, name: ${name}, isSystemIsolate: ${isSystemIsolate}, ' //
        'isolateGroupId: ${isolateGroupId}]';
  }
  
  /// An `Isolate` object provides information about one isolate in the VM.
  