小程序使用wx.uploadFile上传图片到后端,接口调用成功，后端用的MultipartFile接收时候发现缺少boundary参数，后台报错：the request was rejected because no multipart boundary was found，出现的概率大概1%

org.springframework.web.multipart.MultipartException: Failed to parse multipart servlet request;
 nested exception is java.io.IOException: org.apache.tomcat.util.http.fileupload.FileUploadException: 
    the request was rejected because no multipart boundary was found