How to use REST API to do a GET request on a CCM server
One answer
You can use whatever language and library you want, if it supports HTTP communication. I do not know where JazzFormAuthClient comes from. The question is lacking useful details. If JazzFormAuthClient works for you against DNG, why not keep using it against EWM as well?
Otherwise, I share my thoughts on the options about OSLC and REST APIs and how to work with them here: https://rsjazz.wordpress.com/2021/09/29/using-the-ewm-rest-and-oslc-apis/