Angular material io - have item id for the checkbox tree view

I need to have a checkbox tree view which has the id for the checkbox values.In angular documentation example data looks like:

const TREE_DATA = {
  Groceries: {
    'Almond Meal flour': null,
    'Organic eggs': null,
    'Protein Powder': null,
    Fruits: {
      Apple: null,
      Berries: ['Blueberry', 'Raspberry'],
      Orange: null
    }
  },
  Reminders: [
    'Cook dinner',
    'Read the Material Design spec',
    'Upgrade Application to Angular'
  ]
};

In this data i need to have the id as a value along with item name. How can i add this?