This would be a curl example of POSTing form data to ORDS. Seems there's 2 things going on. 1) we don't deal with multipart file uploads and 2) when form data is sent there is no :body since it's parsed apart.
What is the service you are using? I see a webhooks git hub project but guessing that's not it.
We've used webhooks from a number of different 3rd parties for different functionality. It's unfortunate that no two places seem to do it the same, it's a bit like HTTP requests being x-www-form-urlencoded, JSON, XML etc. But this is the first one that's really caused us problems.
Anyway, the one that is causing us problems is SendGrid Incoming Mail (https://sendgrid.com/docs/API_Reference/Webhooks/parse.html). We use SendGrid to send mail and they can also handle incoming mail, but don't have a mailbox. Instead they have a webhook where the incoming mail is forwarded to the webhook. I don't know whether knowing this will provide much help as to test it out you need a SendGrid account and a mail domian pointed at the SendGrid server.
However, you should be able to reproduce the problem using Postman by sending a number of items with a couple of files in the middle.
I've also tried to create my own procedure to handle this, but this hit problems immediately as the procedure parameters need to be named the same as the form items. I could easily pass the subject to my procedure, but there is no way of getting to and from as I would need to have parameters in my procedure called this.
BTW - I've worked around this problem by using a node.js server, which reads the post information and builds a JSON object which is then passed to a RESTful API. I know that the JSON object is built correctly (as we build it), so there is no problem getting the information in the API. It's just unfortunate that I've had to go outside of Oracle to handle this.
Also, I did hit another problem in that one of the form parameters was attachment-info, which you can't pick up in Oracle due to the hyphen (you get a nasty error). When I build the JSON object I replace hyphens with underscores to avoid the issue.
Thanks for your help.