anchor.diff:        var headers;
         if (downloadRange != null) {
           headers = {
  +          'user-agent' : USER_AGENT_STRING,
             'content-type' : CONTENT_TYPE_JSON_UTF8,
             'content-length' : '$length',
             'range' :  'bytes=${downloadRange.start}-${downloadRange.end}',
           };
         } else {
           headers = {
  +          'user-agent' : USER_AGENT_STRING,
             'content-type' : CONTENT_TYPE_JSON_UTF8,
             'content-length' : '$length',
           };
  
positive.code:     });
  
      var headers = {
          'content-type' : "multipart/related; boundary=\"$_boundary\"",
          'content-length' : '$totalLength'
      };
  
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';
  
  