Introduces seen before routes in DefaultRoutingHandler

- to remember the routes that have been visited before

Change-Id: I96470ad5eb0837f7b734ba634c7c3d26e25d03ed
diff --git a/app/src/test/java/org/onosproject/segmentrouting/RouteHandlerTest.java b/app/src/test/java/org/onosproject/segmentrouting/RouteHandlerTest.java
index 2d365a2..6332856 100644
--- a/app/src/test/java/org/onosproject/segmentrouting/RouteHandlerTest.java
+++ b/app/src/test/java/org/onosproject/segmentrouting/RouteHandlerTest.java
@@ -48,6 +48,7 @@
 import org.onosproject.segmentrouting.config.SegmentRoutingDeviceConfig;
 import org.onosproject.store.service.StorageService;
 import org.onosproject.store.service.TestConsistentMap;
+import org.onosproject.store.service.TestConsistentMultimap;
 
 import java.util.Map;
 import java.util.Set;
@@ -158,6 +159,8 @@
         srManager = new MockSegmentRoutingManager(NEXT_TABLE);
         srManager.storageService = createMock(StorageService.class);
         expect(srManager.storageService.consistentMapBuilder()).andReturn(new TestConsistentMap.Builder<>()).anyTimes();
+        expect(srManager.storageService.consistentMultimapBuilder()).andReturn(
+                new TestConsistentMultimap.Builder<>()).anyTimes();
         replay(srManager.storageService);
         srManager.cfgService = new NetworkConfigRegistryAdapter();
         srManager.deviceConfiguration = createMock(DeviceConfiguration.class);