anchor.diff:     * actual instance whenever it is called with the same string name.
      * Creates root logger with logLevel set if not created.
      */
  -  factory Logger(String source, {Map getMetaData()}) {
  +  factory Logger(String source) {
       return _loggers.putIfAbsent(source, source == "" ? _createRootLogger : () => new Logger._named(source));
     }
   
  
positive.code: class Logger {
  
    final source;
    Function getMetaData;
    Level logLevel = null;
    Logger _parent;
    static StreamController _streamController =
  
negative.code:    */
    static Stream<Map> get onRecord => _streamController.stream;
  
    static Function getMetaData;
  
    /**
     * All [Logger]s in the system.
     */
  