private ICompositeValidation <T> UpdateList(string groupName, List <Failure> newFailures)
{
var oldFailures = Failures.Where(x => x.GroupName != groupName).ToList();
if (newFailures.Any() && HasSummaryMessage && !oldFailures.Any())
{
oldFailures.Insert(0, new Failure(this));
}
Failures = new ReadOnlyCollection <Failure>(oldFailures.Concat(newFailures).ToList());
return(this);
}