string GetPresignedManifestUrl(string manifestFileKey) { if (string.IsNullOrEmpty(_presignedManifestUrl)) _presignedManifestUrl = S3Client.GeneratePreSignedURL(this.BucketName, manifestFileKey, AWSSDKUtils.CorrectedUtcNow.AddDays(UrlExpiryPeriod), null); return _presignedManifestUrl; }