code: public void removeSessionProvider(Object key)
     {
        if (sessionProviderKeeper.get() != null)
        {
           sessionProviderKeeper.get().close();
           sessionProviderKeeper.set(null);
        }
  
        if (systemSessionProviderKeeper.get() != null)
        {
           systemSessionProviderKeeper.get().close();
           systemSessionProviderKeeper.set(null);
        }
     }
docs: {@inheritDoc}