An object that provides information about an item (shape or connector) in the Diagram UI component.
Accepted Values: 'shape' | 'connector'
If a user removes an item and then undoes the action, the Diagram inserts the item back and generates a new GUID for its key value. A new GUID is also generated for pasted and cloned items. If you specify key values (IDs in a data source) manually, subscribe to the onInserting data source event to assign the values.