Customfields in plugin not shown

public void start() throws PluginParseException
    {
        init();
        /*some plugins might contain CustomField descriptions.
         * So after all rest of plugin loading, 
         * CustomFieldManager should be refreshed, 
         * so now it can find all CustomField to resolve their instances in db.
         */        
        ComponentManager.getInstance().getCustomFieldManager().refresh();
    }