code: void unregisterInvalidatedSessions() {
  		for (final Map.Entry<String, HttpSession> entry : SESSION_MAP_BY_ID.entrySet()) {
  			final HttpSession session = entry.getValue();
  			if (session.getId() != null) {
  				unregisterSessionIfNeeded(session);
  			} else {
  				// damned JIRA has sessions with null id, when shuting down
  				final String sessionId = entry.getKey();
  				SESSION_MAP_BY_ID.remove(sessionId);
  			}
  		}
  		// issue 198: in JIRA 4.4.*, sessionCreated is called two times with different sessionId
  		// but with the same attributes in the second than the attributes added in the first,
  		// so SESSION_COUNT is periodically counted again
  		SESSION_COUNT.set(SESSION_MAP_BY_ID.size());
  	}
docs: pour Jenkins/jira/confluence/bamboo