docs: protected Object createMyInstance() throws IOException {
          // would like to uninherit from AbstractFactoryBean (but it's final!)
          if (!isSingleton()) {
              throw new RuntimeException("ReloadablePropertiesFactoryBean only works as singleton");
          }
  
          // set listener
          reloadableProperties = new ReloadablePropertiesImpl();
          if (preListeners != null) {
              reloadableProperties.setListeners(preListeners);
          }
  
          // reload
          reload(true);
  
          // add for monitor
          ReloadConfigurationMonitor.addReconfigurableBean((ReconfigurableBean) reloadableProperties);
  
          return reloadableProperties;
      }