return complMultipartUpload.Parts[i].PartNumber < complMultipartUpload.Parts[j].PartNumber
	}) {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidPartOrder), r.URL)
		return
	}

	// Reject retention or governance headers if set, CompleteMultipartUpload spec
	// does not use these headers, and should not be passed down to checkPutObjectLockAllowed

	holdPerms := isPutActionAllowed(ctx, getRequestAuthType(r), dstBucket, dstObject, r, policy.PutObjectLegalHoldAction)
	getObjectInfo := objectAPI.GetObjectInfo

	// apply default bucket configuration/governance headers for dest side.
	retentionMode, retentionDate, legalHold, s3Err := checkPutObjectLockAllowed(ctx, r, dstBucket, dstObject, getObjectInfo, retPerms, holdPerms)
	if s3Err == ErrNone && retentionMode.Valid() {