public BackgroundCertificateSynchronizer(
     INetworkEndpointRefresher refresher,
     INetworkEndpointCache cache,
     INetworkEndpointService endpointService,
     NetworkEndpointConcurrentQueueSet queue,
     ILogger <BackgroundCertificateSynchronizer> logger)
 {
     this.refresher       = refresher;
     this.cache           = cache;
     this.endpointService = endpointService;
     this.queue           = queue;
     log = logger;
 }