Fix javadoc error

Change-Id: I4765b8fa77da381451d8b33d6ac3cbba93f7d1f5
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/meter/Meter.java b/incubator/api/src/main/java/org/onosproject/incubator/net/meter/Meter.java
index 5c59d51..e70dd88 100644
--- a/incubator/api/src/main/java/org/onosproject/incubator/net/meter/Meter.java
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/meter/Meter.java
@@ -62,7 +62,7 @@
     /**
      * The unit used within this meter.
      *
-     * @return
+     * @return the unit
      */
     Unit unit();