Adds an Override to the collection.
This collection supports lazy creates. This means that items in the collection can be referenced without explicitly calling the Add Method and no error will be generated. The items will automatically be created as needed.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2