@Override
    public GuacamoleSession get(String authToken) {
        
        // There are no null auth tokens
        if (authToken == null)
            return null;

        // Return the GuacamoleSession having the given auth token (NOTE: We
        // do not update the access time here, as it is necessary to be able
        // to retrieve and check the session without causing that session to
        // be marked as active. Instead, those updates occur as needed when
        // functions within the GuacamoleSession are invoked.)
        return sessionMap.get(authToken);

    }
Iterates through all active sessions, evicting those sessions which
are beyond the session timeout, or are marked as invalid. Internal
errors which would otherwise stop the session eviction process are
caught, logged, and the process is allowed to proceed.
guacamole/src/main/java/org/apache/guacamole/rest/auth/HashTokenSessionMap.java