webhook subscription event are not sent with validationTokens

Question

I successfully created webhooks to one drive resources and getting I am getting webhook events.
The problem is with the validationTokens property,
that is not being sent, in addition to the value property which contains the array of driveItems.
I could not find any configuration in order to add the validationTokens as mentioned in the section bellow.
please assist if possible.
thanks!

https://learn.microsoft.com/en-us/graph/webhooks-with-resource-data#validating-the-authenticity-of-notifications

the event i'm getting:

{
value: [
{
subscriptionId: 'xxxxx',
clientState: '123',
resource: 'drives/driveid/root/',
tenantId: 'yyyyyyy',
resourceData: null,
subscriptionExpirationDateTime: '2021-02-10T08:00:00-08:00',
changeType: 'updated',
},
],
}

Answer 1

Refer the supported resources section and it talks about what resources it supports.