Gets and sets the property CallerReference. A unique name that ensures the request
            can't be replayed.    If the CallerReference is new (no matter the content of the
            Path object), a new distribution is created.    If the CallerReference is a value
            you already sent in a previous request to create an invalidation batch, and the content
            of each Path element is identical to the original request,    the response includes
            the same information returned to the original request.    If the CallerReference is
            a value you already sent in a previous request to create a distribution but the content
            of any Path is different from the original request,    CloudFront returns an InvalidationBatchAlreadyExists
            error.
            
 Declaration Syntax
 Declaration Syntax| C# | 
public string CallerReference { get; set; }