This is because S3 clients send metadata in NewMultipartUpload but Azure expects metadata to
be set during CompleteMultipartUpload (PutBlockList in Azure terminology). 在NewMultipartUpload期间,我们将客户端发送的元数据存储在内存中,以便以后可以在CompleteMultipartUpload中将其设置在Azure上。如果网关穗启,这些信息也会丢失。