anchor.diff:          if (!_request.hasBody) {
             return null;
           }
  -        return [contentLength];
  +        return [contentLength.toString()];
         case HttpHeaders.CONTENT_TYPE:
           if (contentType == null) {
             return null;
  
positive.code: 
    @override
    void forEach(void f(String name, List<String> values)) => _headers.forEach(f);
  
    @override
    void set host(String _host) {
  
negative.code:     if (val != null) {
        return int.parse(val, onError: (_) => null);
      }
      return int.parse(val);
    }
  
    @override
  