ONOS-6259: Topo2 - Implement server-side highlighting model
- Generated highlights message now sent back to the client
  with the event id "topo2Highlights".

Change-Id: I873ebd38a0636a7d9b5c2a6caf98c6b33de2cc87
diff --git a/core/api/src/main/java/org/onosproject/ui/topo/TopoJson.java b/core/api/src/main/java/org/onosproject/ui/topo/TopoJson.java
index d9edbd7..653b0f9 100644
--- a/core/api/src/main/java/org/onosproject/ui/topo/TopoJson.java
+++ b/core/api/src/main/java/org/onosproject/ui/topo/TopoJson.java
@@ -28,6 +28,7 @@
 public final class TopoJson {
     // package-private for unit test access
     static final String SHOW_HIGHLIGHTS = "showHighlights";
+    static final String TOPO2_HIGHLIGHTS = "topo2Highlights";
 
     static final String DEVICES = "devices";
     static final String HOSTS = "hosts";
@@ -76,6 +77,17 @@
     }
 
     /**
+     * Returns a formatted message ready to send to the topology-2 view
+     * to render highlights.
+     *
+     * @param highlights highlights model to transform
+     * @return fully formatted "show highlights" message
+     */
+    public static ObjectNode topo2HighlightsMessage(Highlights highlights) {
+        return envelope(TOPO2_HIGHLIGHTS, json(highlights));
+    }
+
+    /**
      * Transforms the given highlights model into a JSON message payload.
      *
      * @param highlights the model to transform