ONOS-4971: Synthetic Link Data -- WIP

- Enhancing UiRegion to capture the hierarchical (parent/child) relationships captured in the UiTopoLayouts.

Change-Id: I152e0d52d4580b14b679f3387402077f16f61e6a
diff --git a/core/api/src/main/java/org/onosproject/ui/model/ServiceBundle.java b/core/api/src/main/java/org/onosproject/ui/model/ServiceBundle.java
index 61cf721..6986cf7 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/ServiceBundle.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/ServiceBundle.java
@@ -24,11 +24,20 @@
 import org.onosproject.net.intent.IntentService;
 import org.onosproject.net.link.LinkService;
 import org.onosproject.net.region.RegionService;
+import org.onosproject.ui.UiTopoLayoutService;
 
 /**
  * A bundle of services to pass to elements that might need a reference to them.
  */
 public interface ServiceBundle {
+
+    /**
+     * Reference to a UI Topology Layout service implementation.
+     *
+     * @return layout service
+     */
+    UiTopoLayoutService layout();
+
     /**
      * Reference to a cluster service implementation.
      *