code: @Override
      public final void sessionOpened(NextFilter nextFilter, IoSession session) {
          if (eventTypes.contains(IoEventType.SESSION_OPENED)) {
              IoFilterEvent event = new IoFilterEvent(nextFilter, IoEventType.SESSION_OPENED,
                  session, null); 
              fireEvent(event);
          } else {
              nextFilter.sessionOpened(session);
          }
      }
docs: {@inheritDoc}