// clients expect the ETag header key to be literally "ETag" - not "Etag" (case-sensitive).
	// Therefore, we have to set the ETag directly as map entry.
	w.Header()[xhttp.ETag] = []string{"\"" + etag + "\""}
	hash.TransferChecksumHeader(w, r)

	writeSuccessResponseHeadersOnly(w)
}

// CompleteMultipartUploadHandler - Complete multipart upload.