[ONOS-3851] Initial implementation of Web GUI of CPMan

- Revise chart model to provide default label
- Visualize control message stats per device

Change-Id: I88b8e63ce92114907bba185b1906569fa8cc0b83
diff --git a/apps/cpman/app/src/main/java/org/onosproject/cpman/impl/ControlPlaneManager.java b/apps/cpman/app/src/main/java/org/onosproject/cpman/impl/ControlPlaneManager.java
index f3a29ee..5f0918b 100644
--- a/apps/cpman/app/src/main/java/org/onosproject/cpman/impl/ControlPlaneManager.java
+++ b/apps/cpman/app/src/main/java/org/onosproject/cpman/impl/ControlPlaneManager.java
@@ -81,10 +81,10 @@
             // TODO: this can be changed to switch-case if we have more than
             // one event type
             if (event.type().equals(STATS_UPDATE)) {
-                controlMessages.forEach(c -> {
+                controlMessages.forEach(c ->
                     monitorService.updateMetric(getControlMetric(c), 1,
-                            Optional.of(c.deviceId()));
-                });
+                            Optional.of(c.deviceId()))
+                );
             }
         }
     }