EnumSpeed_03

public static class InvoicePaymentMethodExtensions {
public static bool IsUndefined(this InvoicePaymentMethods paymentMethod) {
        if (paymentMethod == InvoicePaymentMethod.Undefined){
                return true;
            }

            var isDefined = Enum.IsDefined(typeof(InvoicePaymentMethod), paymentMethod);
            return !isDefined;
    }
}