This is not a duplicate referenced question, because it is Spring specific. Whoever added that (3 years after the fact!) didn\'t bother to read the question or comment
This could be your answer: urlencoded Forward slash is breaking URL
I would suggest not putting that in the path, move it to a request param instead.
Work around:
You could change the RequestMapping to
@RequestMapping(value = "/ws/stuff/lookup/resourceId/**", method = RequestMethod.GET)
and then parse the path variables manually from the request object.