public ORMultiValueDictionary <TKey, TValue> Merge(ORMultiValueDictionary <TKey, TValue> other)
{
if (_withValueDeltas == other._withValueDeltas)
{
return(_withValueDeltas
? new ORMultiValueDictionary <TKey, TValue>(Underlying.MergeRetainingDeletedValues(other.Underlying), _withValueDeltas)
: new ORMultiValueDictionary <TKey, TValue>(Underlying.Merge(other.Underlying), _withValueDeltas));
}
throw new ArgumentException($"Trying to merge two ORMultiValueDictionaries of different map sub-types");
}