class CertificateExpirationMonitor {
private:
    class CertificateExpirationMonitorTask : public PeriodicTask {
        std::string taskName() const override;
        void taskDoWork() override;
	
      Mutex _lock;
      const Date_t _certExpiration;
      Date_t _lastCheckTime;
    } 
public:
    static void updateExpirationDeadline(Date_t date);
private:
    static std::unique_ptr<CertificateExpirationMonitorTask> _task;
};