code: public Map<String, Object> appSettings(String key) {
  		if (StringUtils.isBlank(key)) {
  			return appSettings();
  		}
  		return getEntity(invokeGet(Utils.formatMessage("_settings/{0}", key), null), Map.class);
  	}
docs: Returns the value of a specific app setting (property).
  @param key a key
  @return a map containing one element {"value": "the_value"} or an empty map.