public Task <List <InvoiceError> > Handle(ValidateJobInvoiceCommand request, CancellationToken cancellationToken)
        {
            var result = new List <InvoiceError>();

            var invoiceValidator = new InvoiceValidator(request.Job, _ctx);

            if (invoiceValidator.MaterialValidators.Any())
            {
                invoiceValidator.RunMaterialValidators();
            }

            result.AddRange(invoiceValidator.InvoiceErrors);

            return(Task.FromResult <List <InvoiceError> >(result));
        }