private string Execute(PersonStub person)
{
var handler = new ValidationHandler <PersonStub>(
x => !string.IsNullOrWhiteSpace(x.FirstName),
x => $"{nameof(PersonStub.FirstName)} [{x.FirstName}] should not be null or whitespace.");
var message = string.Empty;
handler.InvalidResult += (object sender, Contract.EventArgs.ValidationHandlerArgs e) =>
message = e.ValidationResult.ErrorMessage;
handler.Execute(person);
return(message);
}
