message: Change $filter value from invoicePeriodStartDate to invoicePeriodEndDate
  $filter may be used to filter invoices by invoicePeriodEndDate, not invoicePeriodStartDate. This doc (https://docs.microsoft.com/en-us/rest/api/billing/invoices/list) is for API Version 2017-04-24-preview, so this change should fix the sample request in the doc
diff: "api-version": "2017-04-24-preview",
  "subscriptionId": "subid",
  "$top": "1",
  - "$filter": "invoicePeriodStartDate le 2017-02-01",
  + "$filter": "invoicePeriodEndDate le 2017-02-01",
  "$expand": "downloadUrl"
  },
  "responses": {
  