anchor.diff:    TraceEventWrapper(this.event, this.timeReceived)
         : id = _traceEventWrapperId++;
     final TraceEvent event;
  +
     final num timeReceived;
  +
     final int id;
  +
  +  Map<String, dynamic> get json => event.json;
   
     bool processed = false;
   
  
positive.code: 
    String get name => traceEvents.first.event.name;
  
    Map<String, dynamic> get beginTraceEventJson => traceEvents.first.event.json;
  
    Map<String, dynamic> get endTraceEventJson => traceEvents.last.event.json;
  
    /// Event duration in micros.
    int get duration => (endTime != null) ? endTime - startTime : null;
  
negative.code:       for (TimelineEvent child in children) {
          child.writeTraceToBuffer(buf);
        }
        for (var traceEvent in traceEvents.where(
            (event) => !collectionEquals(event.json, beginTraceEventJson))) {
          buf.writeln(traceEvent.json.toString());
        }
      }
    }
  