Fill "isFavorite" property with correct value

When using the Microsoft Graph an querying

https://graph.microsoft.com/v1.0/me/people

The response will result in

    {
      "id": "8CE6E1DE-CB84-4BF5-971D-D3ECF452E2B5",
      "displayName": "Lorrie Frye",
      "givenName": "Lorrie",
      "jobTitle": "Paralegal",
      "isFavorite": false,
      ...
    },
...

 the  'isFavorite' will always be false, even though a contact was set as favorite via Outlook option 'Add to Favorites'.