code: private void cleanupStaleClients() {
      LocalTime cleanupTime = LocalTime.now();
      LOG.debug("Starting cleanup authentication registry at {}", cleanupTime);
      // Get a list of stale clients under read lock.
      List<UUID> staleChannels = new ArrayList<>();
      for (Map.Entry<UUID, AuthenticatedChannelInfo> clientEntry : mChannels.entrySet()) {
        LocalTime lat = clientEntry.getValue().getLastAccessTime();
        if (lat.plusSeconds(mCleanupIntervalMs / 1000).isBefore(cleanupTime)) {
          staleChannels.add(clientEntry.getKey());
        }
      }
  
      // Unregister stale clients.
      LOG.debug("Found {} stale channels for cleanup.", staleChannels.size());
      for (UUID clientId : staleChannels) {
        unregisterChannel(clientId);
      }
      LOG.debug("Finished state channel cleanup at {}", LocalTime.now());
    }
docs: Primitive that is invoked periodically for cleaning the registry from clients that has become
  stale.