linkify URL for 'request: Connect to <URL> failed' error variant

Spring wraps Apache HttpClient connect failures as 'I/O error on POST request:
Connect to <URL> failed: <reason>'. Same treatment as the RestClient variant:
the URL is embedded in the 'request' word and the 'Connect to ... failed'
restatement is dropped from the visible text.

monitoring/src/main/java/org/thingsboard/monitoring/data/notification/ServiceFailureNotification.java

@@ -52,18 +52,25 @@ public class ServiceFailureNotification implements Notification {
         return String.format("%s - Failure: %s (number of subsequent failures: %s)", serviceKey, errorMsg, failuresCount);
     }
 
-    private static final Pattern REQUEST_URL_PATTERN = Pattern.compile("request for \"(https?://[^\"\\s]+)\"");
+    // Spring RestClient: '... request for "<URL>"'
+    private static final Pattern REQUEST_FOR_URL_PATTERN = Pattern.compile("request for \"(https?://[^\"\\s]+)\"");
+    // Apache HttpClient wrapped by Spring: 'I/O error on POST request: Connect to <URL> failed: <reason>'
+    private static final Pattern REQUEST_CONNECT_PATTERN = Pattern.compile("request: Connect to (https?://\\S+?) failed:");
 
     static String linkifyRequestUrl(String msg) {
         if (msg == null) {
             return null;
         }
-        Matcher m = REQUEST_URL_PATTERN.matcher(msg);
-        if (!m.find()) {
-            return msg;
-        }
         // Slack mrkdwn link: <url|label>
-        return m.replaceAll("<$1|request>");
+        Matcher m = REQUEST_FOR_URL_PATTERN.matcher(msg);
+        if (m.find()) {
+            return m.replaceAll("<$1|request>");
+        }
+        Matcher m2 = REQUEST_CONNECT_PATTERN.matcher(msg);
+        if (m2.find()) {
+            return m2.replaceAll("<$1|request>:");
+        }
+        return msg;
     }
 
     static String stripResponseBody(String msg) {

monitoring/src/test/java/org/thingsboard/monitoring/data/notification/ServiceFailureNotificationTest.java

@@ -55,10 +55,18 @@ class ServiceFailureNotificationTest {
 
     @Test
     void linkifyReplacesRequestForUrlWithSlackMrkdwnLink() {
-        String msg = "503 Service Temporarily Unavailable on POST request for \"https://qa-tb-pe-lts43.iot-private.cloud/api/auth/login\"";
+        String msg = "503 Service Temporarily Unavailable on POST request for \"https://example.com/api/auth/login\"";
 
         assertThat(ServiceFailureNotification.linkifyRequestUrl(msg))
-                .isEqualTo("503 Service Temporarily Unavailable on POST <https://qa-tb-pe-lts43.iot-private.cloud/api/auth/login|request>");
+                .isEqualTo("503 Service Temporarily Unavailable on POST <https://example.com/api/auth/login|request>");
+    }
+
+    @Test
+    void linkifyReplacesRequestConnectToUrlFailed() {
+        String msg = "I/O error on POST request: Connect to https://example.com:443 failed: Connect timed out";
+
+        assertThat(ServiceFailureNotification.linkifyRequestUrl(msg))
+                .isEqualTo("I/O error on POST <https://example.com:443|request>: Connect timed out");
     }
 
     @Test