Detangling incubator: virtual nets, tunnels, resource labels, oh my

- virtual networking moved to /apps/virtual; with CLI & REST API
- tunnels and labels moved to /apps/tunnel; with CLI & REST API; UI disabled for now
- protobuf/models moved to /core/protobuf/models
- defunct grpc/rpc registry stuff left under /graveyard
- compile dependencies on /incubator moved to respective modules for compilation
- run-time dependencies will need to be re-tested for dependent apps

- /graveyard will be removed in not-too-distant future

Change-Id: I0a0b995c635487edcf95a352f50dd162186b0b39
diff --git a/apps/tunnel/api/src/main/java/org/onosproject/incubator/net/tunnel/DefaultLabelStack.java b/apps/tunnel/api/src/main/java/org/onosproject/incubator/net/tunnel/DefaultLabelStack.java
new file mode 100644
index 0000000..1c7ff8c
--- /dev/null
+++ b/apps/tunnel/api/src/main/java/org/onosproject/incubator/net/tunnel/DefaultLabelStack.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * 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.tunnel;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.collect.ImmutableList;
+import org.onosproject.incubator.net.resource.label.LabelResourceId;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * Default implementation of label stack.
+ */
+public class DefaultLabelStack implements LabelStack {
+
+    private final List<LabelResourceId> labelResources;
+
+    /**
+     * Creates label stack.
+     *
+     * @param labelResources contiguous label ids that comprise the path
+     */
+    public DefaultLabelStack(List<LabelResourceId> labelResources) {
+        this.labelResources = ImmutableList.copyOf(labelResources);
+    }
+
+    @Override
+    public List<LabelResourceId> labelResources() {
+        return labelResources;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this)
+                .add("labelResources", labelResources)
+                .toString();
+    }
+
+    @Override
+    public int hashCode() {
+        return labelResources.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj instanceof DefaultLabelStack) {
+            final DefaultLabelStack other = (DefaultLabelStack) obj;
+            return Objects.equals(this.labelResources, other.labelResources);
+        }
+        return false;
+    }
+}