Add ability to administratively remove ports of an offline device.

Change-Id: Iaee085be1cd53f783ed80e7c277403eb65ef6d8f
diff --git a/core/api/src/main/java/org/onosproject/net/device/DeviceAdminService.java b/core/api/src/main/java/org/onosproject/net/device/DeviceAdminService.java
index bfd467c..c95e7e6 100644
--- a/core/api/src/main/java/org/onosproject/net/device/DeviceAdminService.java
+++ b/core/api/src/main/java/org/onosproject/net/device/DeviceAdminService.java
@@ -40,4 +40,13 @@
      * @param enable true if port is to be enabled, false to disable
      */
     void changePortState(DeviceId deviceId, PortNumber portNumber, boolean enable);
+
+    /**
+     * Removes the ports of a device with the specified identifier. The device
+     * must be presently unavailable, i.e. offline.
+     *
+     * @param deviceId device identifier
+     */
+    default void removeDevicePorts(DeviceId deviceId) {
+    }
 }