sender_batch_id in webhook's notification

[wanjas_da]

Hello,

Previously for event type PAYMENT.PAYOUTS-ITEM.SUCCEEDED there always has been sender_batch_id parameter in the request body.

But recently it isn't there anymore.

Is it an intentional change? 

Also, I've failed to find any information on notification's body schemes. Only Webhook simulator gives some insight but without strict definitions. 

Is there more stricter description of webhook's notifications? Am I missing something?

Thank you for your help.