Create a Webhook via API by using the Integration Key - incorrect ClientID

Hello,

here you the two scenarios - both of them are for the same scope - to create a webhook via the API v6.

case #1

I've created the Integration Key (I selected all the scopes) and also I created one Application to obtain the ClientID value - CBJCHBCAABAAKt6f1_xlZvfAj1OBw2cpAxGjLx5MKJz_

When I receive the webhook's validation request, I can see that the X-AdobeSign-ClientId header value CBJCHBCAABAAZZNsPjSoVhGn_jZzS_vERJeoOwgw_gTt is completely different than my Application's ID. Why ?

case #2

I've created the Integration Key (I selected all the scopes) but I haven't created any Application.

When I receive the webhook's validation request, I can see that the X-AdobeSign-ClientId header value also have the value CBJCHBCAABAA8ofgA55rvKLSDktf0MlX6rLxmmuufcNx that is unknown to me. What is it ?