Question: how to obtain accessToken from graphServiceClient?

[alecrt]

I need to call Sharepoint REST Api v1 in order to get comments of a ListItem.

How can I get the accessToken from a client instatiated as follow?

$tokenRequestContext = new ClientCredentialContext(
         $tenantId,
         $clientId,
         $clientSecret
      );
$client = new GraphServiceClient($tokenRequestContext);

[Philip Gichuhi]

There's an ongoing discussion about this here so I'll close this.