anchor.diff:          value = _queryParameters[externalName];
   
           if (value == null && param.httpParameter.isRequired) {
  -          values._missingQueries.add(externalName);
  +          missingQueries.add(externalName);
           }
         } else if (param.httpParameter is HTTPHeader) {
           value = _headerParameters[externalName.toLowerCase()];
   
           if (value == null && param.httpParameter.isRequired) {
  -          values._missingHeaders.add(externalName);
  +          missingHeaders.add(externalName);
           }
         }
   
         if (value != null) {
  -        symbolicatedParameters[sym] = _convertParameterListWithMirror(value, param.typeMirror);
  +        symbolicatedParameterValues[sym] = _convertParameterListWithMirror(value, param.typeMirror);
         }
       });
  -
  -    return symbolicatedParameters;
     }
   
     dynamic _convertParameterListWithMirror(List<String> parameterValues, TypeMirror typeMirror) {
  
positive.code:   }
  
    void _symbolicateControllerParameterValues(_HTTPMethodParameterValues values) {
      values.controllerParametersForRequest = _symbolicateParameterValues(_controllerLevelParameters[_controller.runtimeType], values);
    }
  
    void _symbolicateOptionalParameterValues(_HTTPMethodParameterValues values) {
  
negative.code: 
      var symbolizedCachedParameters = {};
      method.optionalParameters.forEach((name, param) => symbolizedCachedParameters[new Symbol(name)] = param);
      _symbolicateParameterValues(symbolizedCachedParameters, values.optionalParametersForRequest, values._missingQueries, values._missingHeaders);
    }
  
    void _symbolicateParameterValues(Map<Symbol, _HTTPControllerCachedParameter> parameters, Map<Symbol, dynamic> symbolicatedParameterValues, List<String> missingQueries, List<String> missingHeaders) {
      parameters.forEach((sym, param) {
        var externalName = param.httpParameter.externalName;
        List<String> value;
  