I have set up a webhook for an end-of-call report. That works fine. I then tried to add a structured output to the assistant, hoping that it would be included with the end-of-call report. Unfortunately, even though things look good syntactically, that structured output object is not being returned with the end-of-call report (likely because it takes a few seconds, given the LLM call). Can I set up a webhook to fire when that structured object has been created? It seems like that is NOT an option (given the documentation)