How to get Revert payload from PSR-7 compliant request object?

[Cohaven]

Summary

I'm trying to incorporate the revert action into my server code, however, I'm having trouble getting the ID from a PSR-7 compliant request object. I thought that it may be a problem with the revert action using the DELETE method which may not be widely supported, but after customizing the revert action through setOptions to use the POST method, I still can't get the ID.

I've unsuccessfully tried the following methods for retrieving the ID:

1. $body = $request->getParsedBody();
2. $params = $request->getParams();
3. $body2 = $request->getBody();

Google Chrome developer tools network tab does show that there is a Request Payload with the correct ID value in the revert requests.

[Cohaven]

$request->getBody()->getContents() seems to be the right way to get plaintext payload.
This post inspired me to try this option.