Gets and sets the NextMarker property.
            NextMarker is set by S3 only if a Delimiter was specified
            in the original ListObjects request. If a delimiter was
            not specified, the AWS SDK for .NET returns the last Key
            of the List of Objects retrieved from S3 as the NextMarker.
            
 Declaration Syntax
 Declaration Syntax| C# | 
public string NextMarker { get; set; }