Fixing CondecContext javadoc description.

Change-Id: I58125babff31dcf5dd0ba773beee1c7775f11f4d
diff --git a/core/api/src/main/java/org/onosproject/codec/CodecContext.java b/core/api/src/main/java/org/onosproject/codec/CodecContext.java
index 1898e93..7c5ec80 100644
--- a/core/api/src/main/java/org/onosproject/codec/CodecContext.java
+++ b/core/api/src/main/java/org/onosproject/codec/CodecContext.java
@@ -46,7 +46,7 @@
      *
      * @param serviceClass service class
      * @param <T>          service type
-     * @return JSON codec; null if no codec available for the class
+     * @return service implementation; null if no implementation available for the class
      */
     <T> T getService(Class<T> serviceClass);