anchor.diff:  
   class Logger {
   
  +  final fullSource;
     final source;
     Level logLevel = null;
     Logger _parent;
  
positive.code:   static final Map<String, Logger> _loggers = {};
  
    static _createRootLogger() =>
      new Logger._internal("", null)..logLevel = Level.WARNING;
  
    /** Root logger. */
    static Logger get ROOT => new Logger('');
  
negative.code:     if (shouldLog(level)) {
        _streamController.add({
          'level':level,
          'fullSource': fullSource,
          'source':source,
          'event':event,
          'meta':getMetaData != null ? getMetaData() : null,
  