Gets the current key from the enumerator.
Throws an exception because the NullDictionaryEnumerator never has a current value.
As the enumerator is over an empty collection its Current value cannot be moved over a valid position, therefore Key will throw an InvalidOperationException.
| Exception Type | Condition | 
|---|---|
| InvalidOperationException | The collection is empty and Current cannot be positioned over a valid location. | 
NullDictionaryEnumerator Class | log4net.Util Namespace