public async Task <IActionResult> OnClientOffline([FromBody] OnClientOfflinePayload request)
        {
            await ClientOffline(request);

            return(Ok());
        }
 /// <summary>
 /// This event is called if a client using clean_session=false closes the connection or gets disconnected by a duplicate client.
 /// /// For more information <see cref="https://docs.vernemq.com/plugin-development/sessionlifecycle#on_client_offline"/>
 /// </summary>
 /// <param name="clientOfflinePayload">client information</param>
 /// <returns></returns>
 protected virtual async Task ClientOffline(OnClientOfflinePayload clientOfflinePayload)
 {
     return;
 }