Getting Bad Request when I try creating a webhook from my Java API!

I’m getting 400 Bad Request when I try to create a webhook using Java. I have this as my request!

JSONObject requestObj = new JSONObject();
requestObj.put("subscription_url", "URL");
requestObj.put("event_action", "*");
requestObj.put("event_object", "deal");
requestObj.put("user_id", "USER ID");
requestObj.put("version", "2.0");

And am setting my auth token in the header and sending a post request to but no luck! What am I missing?