After charge successful paid or expired you receive this webhook:
Header:
WebhookSignature: <COMPUTED_HMAC_FROM_JSON_BODY_WITH_SECRET_KEY>
Body:
{"code":"XBC12D", //payment code"id":1, //payment id"status":"PAID" // EXPIRED,PAID"meta":{"your-meta-key":"your-meta-value"}}
after successful accepting you need send response:
{"ok":true}