Implementing region hosts for topology 2

Change-Id: I6d1e45b1152b2387d4ff981dc0666868235eb1c3
diff --git a/web/gui/src/test/java/org/onosproject/ui/impl/topo/model/AbstractTopoModelTest.java b/web/gui/src/test/java/org/onosproject/ui/impl/topo/model/AbstractTopoModelTest.java
index de7ec9a..ea48bb1 100644
--- a/web/gui/src/test/java/org/onosproject/ui/impl/topo/model/AbstractTopoModelTest.java
+++ b/web/gui/src/test/java/org/onosproject/ui/impl/topo/model/AbstractTopoModelTest.java
@@ -52,7 +52,6 @@
 import org.onosproject.net.region.DefaultRegion;
 import org.onosproject.net.region.Region;
 import org.onosproject.net.region.RegionId;
-import org.onosproject.net.region.RegionListener;
 import org.onosproject.net.region.RegionService;
 import org.onosproject.ui.UiTopoLayoutService;
 import org.onosproject.ui.impl.AbstractUiImplTest;
@@ -501,8 +500,7 @@
         }
     }
 
-    // TODO: consider implementing RegionServiceAdapter and extending that here
-    private static class MockRegionService implements RegionService {
+    private static class MockRegionService extends RegionServiceAdapter {
 
         private final Map<RegionId, Region> lookup = new HashMap<>();
 
@@ -549,14 +547,6 @@
             }
             return Collections.emptySet();
         }
-
-        @Override
-        public void addListener(RegionListener listener) {
-        }
-
-        @Override
-        public void removeListener(RegionListener listener) {
-        }
     }
 
 
diff --git a/web/gui/src/test/java/org/onosproject/ui/impl/topo/model/RegionServiceAdapter.java b/web/gui/src/test/java/org/onosproject/ui/impl/topo/model/RegionServiceAdapter.java
new file mode 100644
index 0000000..4f7ec4c
--- /dev/null
+++ b/web/gui/src/test/java/org/onosproject/ui/impl/topo/model/RegionServiceAdapter.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.ui.impl.topo.model;
+
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.HostId;
+import org.onosproject.net.region.Region;
+import org.onosproject.net.region.RegionId;
+import org.onosproject.net.region.RegionListener;
+import org.onosproject.net.region.RegionService;
+
+import java.util.Collections;
+import java.util.Set;
+
+/**
+ * Adapter for {@link RegionService}.
+ */
+public class RegionServiceAdapter implements RegionService {
+    @Override
+    public void addListener(RegionListener listener) {
+    }
+
+    @Override
+    public void removeListener(RegionListener listener) {
+    }
+
+    @Override
+    public Set<Region> getRegions() {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public Region getRegion(RegionId regionId) {
+        return null;
+    }
+
+    @Override
+    public Region getRegionForDevice(DeviceId deviceId) {
+        return null;
+    }
+
+    @Override
+    public Set<DeviceId> getRegionDevices(RegionId regionId) {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public Set<HostId> getRegionHosts(RegionId regionId) {
+        return Collections.emptySet();
+    }
+}