javadoc fixes

Change-Id: I3b4fc2d99f42b2413a535fb411b9c19bdd186ad8
diff --git a/core/api/src/main/java/org/onlab/onos/net/DeviceId.java b/core/api/src/main/java/org/onlab/onos/net/DeviceId.java
index 5dcc076..e1080f2 100644
--- a/core/api/src/main/java/org/onlab/onos/net/DeviceId.java
+++ b/core/api/src/main/java/org/onlab/onos/net/DeviceId.java
@@ -48,6 +48,7 @@
      * Creates a device id using the supplied URI.
      *
      * @param uri device URI
+     * @return DeviceId
      */
     public static DeviceId deviceId(URI uri) {
         return new DeviceId(uri);
@@ -57,6 +58,7 @@
      * Creates a device id using the supplied URI string.
      *
      * @param string device URI string
+     * @return DeviceId
      */
     public static DeviceId deviceId(String string) {
         return deviceId(URI.create(string));