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/test/java/org/onosproject/ui/model/AbstractUiModelTest.java b/core/api/src/test/java/org/onosproject/ui/model/AbstractUiModelTest.java
index 5037832..15b3870 100644
--- a/core/api/src/test/java/org/onosproject/ui/model/AbstractUiModelTest.java
+++ b/core/api/src/test/java/org/onosproject/ui/model/AbstractUiModelTest.java
@@ -28,6 +28,7 @@
 import org.onosproject.net.link.LinkService;
 import org.onosproject.net.region.RegionService;
 import org.onosproject.ui.AbstractUiTest;
+import org.onosproject.ui.UiTopoLayoutService;
 
 /**
  * Base class for UI model unit tests.
@@ -42,6 +43,11 @@
     protected static final ServiceBundle MOCK_SERVICES =
             new ServiceBundle() {
                 @Override
+                public UiTopoLayoutService layout() {
+                    return null;
+                }
+
+                @Override
                 public ClusterService cluster() {
                     return MOCK_CLUSTER;
                 }