public static ValidateTarget <TValue?> IsNull <TValue>([ValidatedNotNull] this ValidateTarget <TValue?> target, Func <string> getErrorMessage = null) where TValue : struct { if (target.Value.HasValue) { ExceptionFactory.ThrowException(target.Traits.GenericFailureExceptionType, getErrorMessage != null ? getErrorMessage.Invoke() : ErrorMessageFactory.ShouldBeNull(target)); } return(target); }