code: private JSONObject getOrAddCustomAlert() throws JSONException {
  		JSONObject alert = getCompatibleProperty("alert", JSONObject.class, "A simple alert (\"%s\") was already added to this payload");
  		if (alert == null) {
  			alert = new JSONObject();
  			put("alert", alert, this.apsDictionary, false);
  		}
  		return alert;
  	}
docs: Get the custom alert object, creating it if it does not yet exist.
  
  @return the JSON object defining the custom alert
  @throws JSONException if a simple alert has already been added to this payload