by adding processing of metadata and tagging in s3 api CopyObject (judging whether to copy or overwrite according to the directive header)
see https://blog.aqwari.net/xml-schema-go/ 1. go get aqwari.net/xml/cmd/xsdgen 2. xsdgen -o s3api_xsd_generated.go -pkg s3api AmazonS3.xsd