[ONOS-5686] Re-naming and re-constructing virtual network classes

Changes.
1. Named *Service classes in the impementation package re-named as
   *Manager
2. VirtualTopologyProvider is renamed as DefaultVirtualNetworkProvider

Change-Id: Ic8663aee793d0b8f87ffea3df7f71c8ac77362ca
diff --git a/incubator/net/src/main/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkPathManager.java b/incubator/net/src/main/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkPathManager.java
new file mode 100644
index 0000000..ad81141
--- /dev/null
+++ b/incubator/net/src/main/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkPathManager.java
@@ -0,0 +1,82 @@
+/*
+ * 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.incubator.net.virtual.impl;
+
+import org.onosproject.incubator.net.virtual.VirtualNetwork;
+import org.onosproject.incubator.net.virtual.VirtualNetworkService;
+import org.onosproject.incubator.net.virtual.VnetService;
+import org.onosproject.net.DisjointPath;
+import org.onosproject.net.ElementId;
+import org.onosproject.net.Link;
+import org.onosproject.net.Path;
+import org.onosproject.net.host.HostService;
+import org.onosproject.net.topology.LinkWeight;
+import org.onosproject.net.topology.PathService;
+import org.onosproject.net.topology.AbstractPathService;
+import org.onosproject.net.topology.TopologyService;
+
+import java.util.Map;
+import java.util.Set;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Path service implementation built on the virtual network service.
+ */
+public class VirtualNetworkPathManager
+        extends AbstractPathService
+        implements PathService, VnetService {
+
+    private static final String NETWORK_NULL = "Network ID cannot be null";
+
+    private final VirtualNetwork network;
+
+    /**
+     * Creates a new virtual network path service object.
+     *
+     * @param virtualNetworkManager virtual network manager service
+     * @param network               virtual network
+     */
+
+    public VirtualNetworkPathManager(VirtualNetworkService virtualNetworkManager,
+                                     VirtualNetwork network) {
+        checkNotNull(network, NETWORK_NULL);
+        this.network = network;
+        topologyService = virtualNetworkManager.get(network.id(), TopologyService.class);
+        hostService = virtualNetworkManager.get(network.id(), HostService.class);
+    }
+
+    @Override
+    public Set<Path> getPaths(ElementId src, ElementId dst) {
+        return getPaths(src, dst, null);
+    }
+
+    @Override
+    public Set<DisjointPath> getDisjointPaths(ElementId src, ElementId dst) {
+        return getDisjointPaths(src, dst, (LinkWeight) null);
+    }
+
+    @Override
+    public Set<DisjointPath> getDisjointPaths(ElementId src, ElementId dst,
+                                              Map<Link, Object> riskProfile) {
+        return getDisjointPaths(src, dst, null, riskProfile);
+    }
+
+    @Override
+    public VirtualNetwork network() {
+        return network;
+    }
+}