improve assert

Original commit: elastic/x-pack-elasticsearch@cfedeb5da8

src/main/java/org/elasticsearch/alerts/AlertsStore.java

@@ -112,11 +112,17 @@ public class AlertsStore extends AbstractComponent {
         alert.version(response.getVersion());
 
         // Don'<></> need to update the alertMap, since we are working on an instance from it.
-        assert alertMap.get(alert.alertName()) == alert;
+        assert verifySameInstance(alert);
 
         return response;
     }
 
+    private boolean verifySameInstance(Alert alert) {
+        Alert found = alertMap.get(alert.alertName());
+        assert found == alert : "expected " + alert + " but got" + found;
+        return true;
+    }
+
     /**
      * Deletes the alert with the specified name if exists
      */