private string MappKey(string key)
{
// this is a special case for DataSource key, that is atipical
if (String.Equals(key, "DataSource", StringComparison.InvariantCultureIgnoreCase))
return "DataSource";
string outKey;
if (!keymaps.TryGetValue(key, out outKey))
throw new ArgumentException("The connection string keyword is not supported: " + key);
return outKey;
}