code: public void addAppSetting(String key, Object value) {
  		if (!StringUtils.isBlank(key) && value != null) {
  			invokePut(Utils.formatMessage("_settings/{0}", key), Entity.json(Collections.singletonMap("value", value)));
  		}
  	}
docs: Adds or overwrites an app-specific setting.
  @param key a key
  @param value a value