if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	_, isEncrypted := crypto.IsEncrypted(mi.UserDefined)

	// Read compression metadata preserved in the init multipart for the decision.
	_, isCompressed := mi.UserDefined[ReservedMetadataPrefix+"compression"]
	// Compress only if the compression is enabled during initial multipart.
	var idxCb func() []byte
	if isCompressed {