docs: private void expireOrphanSessions(long timestamp) {
      // Iterate through registered sessions.
      for (RaftSession session : raft.getSessions().getSessions()) {
        if (session.getService().deleted() && session.isTimedOut(timestamp)) {
          logger.debug("Orphaned session expired in {} milliseconds: {}", timestamp - session.getLastUpdated(), session);
          session = raft.getSessions().removeSession(session.sessionId());
          if (session != null) {
            session.expire();
          }
        }
      }
    }