anchor.diff:  
     String _pathPrefix;
   
  -  /// Value for the "Via" header.
  -
  -  final String _via;
  +  /// Identifies this proxy in "Via" headers this proxy will add.
  +
  +  final String _receivedBy;
   
     /// Indicates if a Via header is added to the response.
  +  ///
  +  /// Adding a Via header into the HTTP response is optional. This member
  +  /// controls whether it is added or not.
   
     final bool includeViaHeaderInResponse;
   
  
positive.code:     'proxy-authenticate',
    ];
  
    // Default value to use for the "Via" header when forwarding the request.
    // Used when no value of via was provided.
  
    static const String _viaDefault = '1.1 woomera_proxy';
  
    //================================================================
    // Members
  
negative.code:     // Again, since _http.get_ does not support multiple headers, if there are
      // any existing Via header(s), their values are concatenated together
      // with the new value and separated by a comma.
  
      String protocolVersion;
      final core = req._coreRequest;
      if (core is _CoreRequestReal) {
        protocolVersion = core._httpRequest.protocolVersion;
      } else {
        protocolVersion = '1.1'; // not a real HTTP request: assume common value
      }
  
      final _via = '$protocolVersion $_receivedBy';
  
      final _newVia = req.headers['via'] != null
          ? '${req.headers['via'].where((s) => s.isNotEmpty).join(', ')}, $_via'
  