public static void CheckForIllegalFilters(Dictionary<CrontabFieldKind, List<ICronFilter>> filters)
{
var monthSingle = GetSpecificFilters(filters, CrontabFieldKind.Month);
var daySingle = GetSpecificFilters(filters, CrontabFieldKind.Day);
if (monthSingle.Any() && monthSingle.All(x => x.SpecificValue == 2))
{
if (daySingle.Any() && daySingle.All(x => (x.SpecificValue == 30) || (x.SpecificValue == 31)))
throw new CrontabException("Nice try, but February 30 and 31 don't exist.");
}
}