REST API - Notification setup

Hi, I’m integrating my volumio system with an older automation system that only provides low level assistance for network connections, i.e. socket level connect, send, receive. I’m using Postman and Wireshark to validate the REST API requests and responses before coding the automation app as I need to construct and parse all the requests by hand. A number of requests that I’ve tried work fine but I’m having an issue with setting up notifications.

I based my request on the example in the REST API (…/api/v1/pushNotificationUrls?url=http://…endpoint…)
I can only get it to work with the Body (and the parameter is unnecessary). Using just the Parameter form (above), it always returns {“error”: “Missing URL parameter”}. I’ve tried it with a few different Content-type choices based on other community posts, but no success. Can someone point me in the right direction?

I can construct the Body version if need be, but using the Parameter version would be simpler. More importantly I may be misunderstanding how this request should work and would like to get clear on it.

Thanks for any help,

Volumio Version: 2.873
Hardware: Pi 4
DAC: HiBerry DAC2 HD