Adding device driver inheritance mechanism.

Change-Id: I9c883d32ce0c39f961eddd5c4624dc23f794fe4d
diff --git a/core/api/src/test/java/org/onosproject/net/driver/DefaultDriverProviderTest.java b/core/api/src/test/java/org/onosproject/net/driver/DefaultDriverProviderTest.java
index adfa486..4568fd9 100644
--- a/core/api/src/test/java/org/onosproject/net/driver/DefaultDriverProviderTest.java
+++ b/core/api/src/test/java/org/onosproject/net/driver/DefaultDriverProviderTest.java
@@ -28,15 +28,15 @@
     @Test
     public void basics() {
         DefaultDriverProvider ddp = new DefaultDriverProvider();
-        DefaultDriver one = new DefaultDriver("foo.bar", "Circus", "lux", "1.2a",
+        DefaultDriver one = new DefaultDriver("foo.bar", null, "Circus", "lux", "1.2a",
                                               ImmutableMap.of(TestBehaviour.class,
                                                               TestBehaviourImpl.class),
                                               ImmutableMap.of("foo", "bar"));
-        DefaultDriver two = new DefaultDriver("foo.bar", "", "", "",
+        DefaultDriver two = new DefaultDriver("foo.bar", null, "", "", "",
                                               ImmutableMap.of(TestBehaviourTwo.class,
                                                               TestBehaviourTwoImpl.class),
                                               ImmutableMap.of("goo", "wee"));
-        DefaultDriver three = new DefaultDriver("goo.foo", "BigTop", "better", "2.2",
+        DefaultDriver three = new DefaultDriver("goo.foo", null, "BigTop", "better", "2.2",
                                                 ImmutableMap.of(TestBehaviourTwo.class,
                                                                 TestBehaviourTwoImpl.class),
                                                 ImmutableMap.of("goo", "gee"));