plus.createDownloadTask方法暂停下载再点击继续下载后，返回的downloadedSize大小有问题

    var pkAttach = item.affixId;  
            var fileName = item.fileName;  
            var fileTempName = pkAttach + ".tmp";  
            var filePath = pkAttach;  
            var fullFilePath = "_downloads/"+ filePath;  
            var downFilePathName = filePath + fileName;  
            var downFileTempPathName = filePath + fileTempName;  
            var percent = "";  
var task =plus.createDownloadTask(url, downFileTempPathName, function(task, status) {  
                if(url.indexOf("assetsManageAction_downFile.do") != -1||url.indexOf("knowledge_downloadKnowledgeAttr.do") != -1||url.indexOf("notice_downloadNoticeAttr.do") != -1||url.indexOf("myWork_downloadWorkAttr.do") != -1) {  
                    if(task.__responseHeaders__.totalSize==0){  
                        mui.toast("文件为空");  
                        item.state='no';  
                        context.$set(context.trueItems, index, item)  
                        return;  
                    };  
                };  
                var realFileTempName = task.filename.replace(fullFilePath, ""); //有时候下载失败也会生成临时文件，而系统默认会追加数字命名，所以这里以实际返回的下载成功文件名为依据  
                plus.io.resolveLocalFileSystemURL(fullFilePath, function(pathEntry) { //打开父目录  
                    pathEntry.getFile(realFileTempName, { //找到临时文件  
                        create: false  
                    }, function(temFileEntry) {  
                        //把临时文件名改成实际文件名  

                        var tempFileName = fileName;  
                        //当文件名过长时,截取一个短的名称,防止过长时无法存在我们的手机中  

                        var tmp = fileName.split(".");  
                        //先判断当前文件是否有后缀名  
                        if(tmp.length > 0) {  
                            if(tmp[0].length > 40) {  
                                tempFileName = tmp[0].substr(0, 40) + "." + tmp[1];  
                            }  
                        } else {  
                            if(fileName.length > 0) {  
                                tempFileName = fileName.substr(0, 40);  
                            }  
                        }  
                        context.tempFileName = tempFileName;  
                        context.moveTempToReal(pathEntry, temFileEntry, pkAttach, fileName, tempFileName, 0);  
                    }, function(e) {  
                        item.state = 'no';  
                        context.$set(context.trueItems, index, item)  
                        mui.toast("[" + fileName + "]下载失败,解析临时文件失败:" + e.message);  
                    });  
                }, function(e) {  
                    item.state = 'no';  
                    context.$set(context.trueItems, index, item)  
                    mui.toast("[" + fileName + "]下载失败,解析临时目录失败:" + e.message);  
                });  
            }, function(msg) {  
                item.state = 'no';  
                context.$set(context.trueItems, index, item)  
                mui.toast("[" + fileName + "]下载失败:" + msg);  
            }, function(task, status) {  
                if(url.indexOf("assetsManageAction_downFile.do") != -1||url.indexOf("knowledge_downloadKnowledgeAttr.do") != -1||url.indexOf("notice_downloadNoticeAttr.do") != -1||url.indexOf("myWork_downloadWorkAttr.do") != -1) {  
                    percent = Math.floor((task.downloadedSize / task.__responseHeaders__.totalSize) * 100);  
                } else {  
                    percent = Math.floor((task.downloadedSize / task.totalSize) * 100);  
                }  

            });  

            this.attachmentObj.startDownloadTask(task);  
            //把任务对象与当前下载关联并缓存  
            item.taskId = task.id;  
            this.taskJson[task.id] = task;  

pauseDownloadTask = function (dtask){  
    console.log("pause--taskId:" + item.taskId + "  taskTemp--downloadedSize:" + JSON.stringify(taskTemp.downloadedSize));  
    dtask.pause();  
}  

resumeDownloadTask = function (dtask){  
    console.log("resume--taskId:" + item.taskId + "  taskTemp--downloadedSize:" + JSON.stringify(taskTemp.downloadedSize));  
    dtask.resume();  
}

问题描述：
点击附件下载暂停，然后点击继续下载，下载任务返回的download文件已下载的大小就会出现问题。
打印的日志：
pause--taskId:dt61537263165959 taskTemp--downloadedSize:487376
resume--taskId:dt61537263165959 taskTemp--downloadedSize:945522
pause--taskId:dt61537263165959 taskTemp--downloadedSize:774144

这到底是什么原因呢？