anchor.diff:      });
   
       var headers = {
  +        'user-agent' : USER_AGENT_STRING,
           'content-type' : "multipart/related; boundary=\"$_boundary\"",
           'content-length' : '$totalLength'
       };
  
positive.code:       var headers;
        if (downloadRange != null) {
          headers = {
            'content-type' : CONTENT_TYPE_JSON_UTF8,
            'content-length' : '$length',
            'range' :  'bytes=${downloadRange.start}-${downloadRange.end}',
          };
        } else {
          headers = {
            'content-type' : CONTENT_TYPE_JSON_UTF8,
            'content-length' : '$length',
          };
  
negative.code: import "package:crypto/crypto.dart" as crypto;
  import "../common/common.dart" as common_external;
  import "package:http/http.dart" as http;
  
  const String USER_AGENT_STRING =
      'google-api-dart-client ${config.name}/${config.version}';
  
  """ + r"""
  const CONTENT_TYPE_JSON_UTF8 = 'application/json; charset=utf-8';
  
  