code: private Session removeSession(String id) {
          try {
              Session session = sessionCache.delete(id);
              if (session != null) {
                  session.beginInvalidate();
                  for (int i = sessionListeners.size() - 1; i >= 0; i--) {
                      sessionListeners.get(i).sessionDestroyed(session);
                  }
              }
              return session;
          } catch (Exception e) {
              log.warn("Failed to delete session", e);
              return null;
          }
      }
docs: Remove session from manager.
  
  @param id the session to remove
  @return if the session was removed