[ODTN] Interface of a new driver behavior for checking internal connectivity in a device.

This would be used mostly for optical devices which typically have many connectivity constraints.

The patch also includes a CLI command to using driver behavior and an empty driver implementation.

patch 1: first draft: behaviour, CLI, empty driver, xml.

patch 2,3,4,6: checkstyle.

patch 5: comments by Andrea.

Change-Id: Ia1573a9f14b49c39c96fa3351ccc37988f1526ec
diff --git a/core/api/src/main/java/org/onosproject/net/behaviour/InternalConnectivity.java b/core/api/src/main/java/org/onosproject/net/behaviour/InternalConnectivity.java
new file mode 100644
index 0000000..c8e7bf9
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/behaviour/InternalConnectivity.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2020-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.
+
+ * This work was partially supported by EC H2020 project METRO-HAUL (761727).
+ */
+
+package org.onosproject.net.behaviour;
+
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.driver.HandlerBehaviour;
+
+import java.util.Set;
+
+/**
+ * Handler behaviour for retrieving internal connectivity information.
+ */
+public interface InternalConnectivity extends HandlerBehaviour {
+    /**
+     * Test if two ports of the device can be internally connected.
+     *
+     * @param inputPort in port of device
+     * @param outputPort out port of device
+     * @return true if inputPort can be connected outputPort
+     */
+    boolean testConnectivity(PortNumber inputPort, PortNumber outputPort);
+
+    /**
+     * Returns the set of output ports that can be connected to inputPort.
+     *
+     * @param inputPort in port of device
+     * @return list of output ports that can be connected to inputPort
+     */
+    Set<PortNumber> getOutputPorts(PortNumber inputPort);
+
+    /**
+     * Returns the set of input ports that can be connected to outputPort.
+     *
+     * @param outputPort out port of device
+     * @return list of input ports that can be connected to outputPort
+     */
+    Set<PortNumber> getInputPorts(PortNumber outputPort);
+}