@Override
	public synchronized ID removeOnline(final USER user)
	{
		final ID sessionId = super.removeOnline(user);
		if (sessionId != null)
		{
			sessionIdToSession.remove(sessionId);
		}
		return sessionId;
	}
@ Override public synchronized ID removeOnline ( final USER user ) { final ID sessionId = super . removeOnline ( user ) ; if ( sessionId != null ) { sessionIdToSession . remove ( sessionId ) ; } return sessionId ; }
Removes the user from the map. This method shell be invoked when the session is unbounded
from the Application. In wicket is the best way to do that in the
{@code WebApplication#sessionUnbound(String)}.

@param user
the user
@return the session id