1)Call to removed method 'generate' found for 'Ext.data.UuidGenerator' 2)Usage of removed Class 'Ext.data.UuidGenerator' found.

This 2 errors are coming while migration

itemId: 'mailGrid_' + new Ext.data.UuidGenerator().generate(),

please suggest me what I can use instead of this I Tried Ext.data.identifier.Uuid but it is not working