public FeatureToggle AddNewFeatureToggle(string key, string description)
{
Guard.IsFalse(FeatureToggles.Any(x => x.Key == key), "Duplicated key for this application");
var featureToggle = FeatureToggle.New(key, description, this);
FeatureToggles.Add(featureToggle);
return(featureToggle);
}