public TransactionSpecificationBase AddService(string service, int?version = null)
        {
            var serviceToBeAdded = new SpecificationRequestedService()
            {
                Name    = service,
                Version = version,
            };

            this.Services.Add(serviceToBeAdded);

            return(this);
        }
        public TransactionSpecificationBase AddService(SpecificationRequestedService addedService)
        {
            this.Services.Add(addedService);

            return(this);
        }