Adding more unit tests.
Made some classes abstract which should have been.
diff --git a/core/api/src/test/java/org/onlab/onos/net/DefaultDeviceTest.java b/core/api/src/test/java/org/onlab/onos/net/DefaultDeviceTest.java
index ea1c8fd..f7bc617 100644
--- a/core/api/src/test/java/org/onlab/onos/net/DefaultDeviceTest.java
+++ b/core/api/src/test/java/org/onlab/onos/net/DefaultDeviceTest.java
@@ -40,6 +40,18 @@
     @Test
     public void basics() {
         Device device = new DefaultDevice(PID, DID1, SWITCH, MFR, HW, SW, SN1);
+        validate(device);
+    }
+
+    @Test
+    public void annotations() {
+        Device device = new DefaultDevice(PID, DID1, SWITCH, MFR, HW, SW, SN1,
+                                          DefaultAnnotations.builder().set("foo", "bar").build());
+        validate(device);
+        assertEquals("incorrect provider", "bar", device.annotations().value("foo"));
+    }
+
+    private void validate(Device device) {
         assertEquals("incorrect provider", PID, device.providerId());
         assertEquals("incorrect id", DID1, device.id());
         assertEquals("incorrect type", SWITCH, device.type());
@@ -50,4 +62,4 @@
         assertEquals("incorrect serial", SN1, device.serialNumber());
     }
 
-}
+}
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