Retrieves the contact Id and name of each contact group

Example response

{
  "ContactGroups": [
    {
      "Contacts": [
        {
          "UpdatedDateUTC": "/Date(1573755038314)/",
          "BrandingTheme": {
            "CreatedDateUTC": "/Date(1573755038314)/"
          },
          "BatchPayments": {
            "BankAccountNumber": "123-456-1111111",
            "BankAccountName": "ACME Bank",
            "Details": "Hello World",
            "Code": "ABC",
            "Reference": "Foobar"
          },
          "Attachments": [
            {
              "AttachmentID": "00000000-0000-0000-0000-000000000000",
              "FileName": "xero-dev.jpg",
              "Url": "https://api.xero.com/api.xro/2.0/Accounts/da962997-a8bd-4dff-9616-01cdc199283f/Attachments/sample5.jpg",
              "MimeType": "image/jpg"
            }
          ]
        }
      ]
    }
  ]
}