code: public void fireSessionCreated(IoSession session) {
          boolean firstSession = false;
          if (session.getService() instanceof IoConnector) {
              synchronized (managedSessions) {
                  firstSession = managedSessions.isEmpty();
              }
          }
  
          // If already registered, ignore.
          if (managedSessions.putIfAbsent(session.getId(), session) != null) {
              return;
          }
  
          // If the first connector session, fire a virtual service activation event.
          if (firstSession) {
              fireServiceActivated();
          }
  
          // Fire session events.
          IoFilterChain filterChain = session.getFilterChain(); 
          filterChain.fireSessionCreated();
          filterChain.fireSessionOpened();
  
          int managedSessionCount = managedSessions.size();
          if (managedSessionCount > largestManagedSessionCount) {
              largestManagedSessionCount = managedSessionCount;
          }
          cumulativeManagedSessionCount ++;
  
          // Fire listener events.
          for (IoServiceListener l : listeners) {
              try {
                  l.sessionCreated(session);
              } catch (Throwable e) {
                  ExceptionMonitor.getInstance().exceptionCaught(e);
              }
          }
      }
docs: Calls {@link IoServiceListener#sessionCreated(IoSession)} for all registered listeners.