Private _isPrivate _itemsTest whether the set has been disposed.
Add a disposable item to the set.
Test whether the set contains a specific item.
The item of interest.
true if the set contains the item, false otherwise.
Dispose of the set and the items it contains.
Items are disposed in the order they are added to the set.
Remove a disposable item from the set.
An object which manages a collection of disposable items.