See https://github.com/comodal/pagerduty-client
The core library aims to have minimum dependencies (java.base, java.net.http). A JSON response parsing module is provided which relies on the module systems.comodal.json_iterator, but it is easy to provide your own adapter if a different JSON parsing library is preferred.
Posting here to try to get it added to https://v2.developer.pagerduty.com/docs/libraries.