I'm no http request expert but I've banged my head against this problem enough times to know that POST requests usually require a bit more than just passing info through the uri. Most times it requires you to choose a content type (json, txt, html, etc) and sometimes requires content to be included in the header and/or body.
Like I said, I'm no expert, but I use the Postman application and try every combination I can think of till is succumbs to my ignorance/stubbornness. In your case I suspect that your content type is "application/json".
This is awesome, does exactly what I wanted
Do you use Kodi @stephack?
There is another ST app that I think @josh also wrote... One that reads Kodi state. I was using this in ST to track videoplaying status and change lighting when we played a movie. I have been unable to get this working fully in ST. I am able to pause / play etc from Hubitat but unable to get any info back
The state driven part of the ST-Kodi app relies on UPnP eventing. It works best with Kodi devices that are kept ON all the time so it can keep the UPnP event subscriptions in place.
It has some fall backs using the associated SmartApp for scheduling healthchecks on the UPnP subscriptions... so unless you've ported both the DTH and the SmartApp, you may experience some difficulty with the UPnP event subscriptions.
(Similarly, some Android devices are weird about UPnP eventing and block it)
Edit: And it has a manual fallback where tapping refresh will query for the current state rather than waiting for events.
I've managed to get the App and Driver installed but device discovery didn't find anything...
I manually added the info into the settings on the driver screen and have been able to send notificiations, play, pause, etc... basically all the buttons seem to do what they are intended. But I don't see any status returned. I have just noted your comment about Android though, I am using an Nvidia Shield
Yeah, there's probably a few things that would need to be tweaked from the SmartThings version of the driver to get it to work in Hubitat. By manually entering the configuration details into the driver, you get the basic control capabilities which all happen over HTTP, but UPnP events won't work properly without the SmartApp. Here's a thread that covers many porting details:
Like, @stephack, I haven't personally used Kodi in several years so I didn't port the DTH/SmartApp over... but the code is out there and anyone is welcome to port it and take stewardship!