public void SetKeyValue(string key, string value)
{
bool IsMatch(PointOfSaleKeyValue posKv) => string.Equals(posKv.Key, key, StringComparison.OrdinalIgnoreCase);
var cnt = KeyValues.Count(IsMatch);
if (cnt > 1)
{
foreach (var kv in KeyValues.Where(IsMatch).ToArray())
{
KeyValues.Remove(kv);
}
}
else if (cnt == 1)
{
KeyValues.First(IsMatch).SetValue(value);
}
else
{
KeyValues.Add(new PointOfSaleKeyValue(key, value));
}
}