I am using the Java wrapper in my project.
I am calling: prince.setBaseUrl(http://127.0.0.1:9876/resources);

I was expecting prince to call that baseurl with a resource filename (images, etc.) so I set up a controller request mapping to: @GetMapping("/resources/{resourceName}")
However prince never seems to call this endpoint.

I set up another mapping for @GetMapping("/{resourceName") and Prince DOES call this one.

Is it expected that the "resources" part of the baseurl is stripped off?

Yes, the base URL represents the nominal URL of the input document that relative paths will be resolved against.