Fixing 4 javadoc warnings in onos-api

Change-Id: Ib9fe457b463adfb81b5f8a601ce67eb11575f439
diff --git a/core/api/src/main/java/org/onosproject/store/service/AtomicCounterBuilder.java b/core/api/src/main/java/org/onosproject/store/service/AtomicCounterBuilder.java
index 1f5400a..f3b6c8f 100644
--- a/core/api/src/main/java/org/onosproject/store/service/AtomicCounterBuilder.java
+++ b/core/api/src/main/java/org/onosproject/store/service/AtomicCounterBuilder.java
@@ -48,6 +48,7 @@
      * <p>
      * Note: Must be set when retries are enabled
      * </p>
+     * @param executor executor service
      * @return this AtomicCounterBuilder
      */
     AtomicCounterBuilder withRetryExecutor(ScheduledExecutorService executor);