Remove messages for non-ERROR can_connect service checks (#369)

* Remove messages for non-ERROR can_connect service checks

* Modify logic to be more straightforward

* Remove warn status

* Change to if status is not error

src/main/java/org/datadog/jmxfetch/App.java

@@ -839,6 +839,11 @@ private void sendServiceCheck(
     private void sendCanConnectServiceCheck(Reporter reporter, String checkName,
         String serviceCheckPrefix, String status, String message, String[] tags) {
         String serviceCheckName = String.format("%s.can_connect", serviceCheckPrefix);
+
+        if (status != Status.STATUS_ERROR) {
+            message = null;
+        }
+
         reporter.sendServiceCheck(
                 checkName, serviceCheckName, status, message, tags);
     }

src/test/java/org/datadog/jmxfetch/TestServiceChecks.java

@@ -74,8 +74,9 @@ public void testServiceCheckWarning() throws Exception {
         assertNotNull(sc.get("name"));
         assertNotNull(sc.get("status"));
 
-        // Message should not be null anymore and reports a high number of metrics warning
-        assertNotNull(sc.get("message"));
+        // Despite there being a high number of metrics warning, message should be null.
+        // Non-ERROR statuses are set to OK, and OK statuses should have null messages.
+        assertNull(sc.get("message"));
         assertNotNull(sc.get("tags"));
 
         String scName = (String) (sc.get("name"));