使用Google Drive SDK上传JSON文件是零字节（javascript）

Question

        var metadata = {
            'title': ufilename,
            'mimeType': contentType,
            'modifiedDate' : modifiedDate,
            'parents': [{'id':parentGuid}]
        };

        var multipartRequestBody =
            delimiter +
            'Content-Type: application/json\r\n\r\n' +
            JSON.stringify(metadata) +
            delimiter +
            'Content-Type: ' + contentType + '\r\n' +
            '\r\n' +
            JSON.stringify(jsonObj) +
            close_delim;

        var reqObj = {
                'path': '/upload/drive/v2/files',
                'method': 'POST',
                'params': {'uploadType': 'multipart'},
                'headers': {
                  'Content-Type': 'multipart/mixed; boundary="' + boundary + '"'
                },
                'body': multipartRequestBody
        };

        var request = gapi.client.request(reqObj);

headers: Content-Type: "multipart/mixed; boundary="-------314159265358979323846"
method: "POST"
params: uploadType: "multipart"
path: "https://www.googleapis.com/upload/drive/v2/files"
body:
---------314159265358979323846
Content-Type: application/json

{"title":"survey.json","mimeType":"application/octet-stream","modifiedDate":"2014-10-24T08:17:45.099-06:00","parents":[{"id":"0B4ho7vdmkgJOczc4NENqd0d0TDg"}]}
---------314159265358979323846
Content-Type: application/octet-stream

{"model":{"DateTime":{"type":"datetime","required":true},"Bird":{"type":"string"},"Photo":         {"type":"image"},"Notes":{"type":"string"},"Location":{"type":"geopoint"}},"settings":[{"setting":"form_id","value":"birdwatching"},{"setting":"form_version","value":1},{"setting":"form_category","value":"Tracking"},{"setting":"form_title","value":"Bird Watching"}],"survey":[{"name":"DateTime","type":"datetime","label":"Date and Time"},{"name":"Location","type":"geopoint","label":"Location"},{"name":"Bird","type":"string-auto","label":"Bird"},{"type":"text","name":"Notes","label":"Notes"},{"name":"Photo","type":"image","label":"Photo"}],"choices":{}}
---------314159265358979323846--