Add certificate in http fallback handler

Author: w1am

src/EventStore.Client/HttpFallback.cs

@@ -17,11 +17,16 @@ internal HttpFallback (EventStoreClientSettings settings) {
             _defaultCredentials = settings.DefaultCredentials;
 
 			var handler = new HttpClientHandler();
-			if (!settings.ConnectivitySettings.Insecure && !settings.ConnectivitySettings.TlsVerifyCert) {
+			if (!settings.ConnectivitySettings.Insecure) {
 				handler.ClientCertificateOptions = ClientCertificateOption.Manual;
-				handler.ServerCertificateCustomValidationCallback = (_, _, _, _) => true;
+
+				if (settings.ConnectivitySettings.TlsCaFile != null)
+					handler.ClientCertificates.Add(settings.ConnectivitySettings.TlsCaFile);
+
+				if (!settings.ConnectivitySettings.TlsVerifyCert)
+					handler.ServerCertificateCustomValidationCallback = (_, _, _, _) => true;
 			}
-			
+
 			_httpClient = new HttpClient(handler);
 			if (settings.DefaultDeadline.HasValue) {
 				_httpClient.Timeout = settings.DefaultDeadline.Value;