Fix Javadoc warnings

Change-Id: I2975b3d7bb581d5574969037e1f99401b94ef3dc

@@ -28,7 +28,9 @@ public interface DemoAPI {
 
     /**
      * Tests flow subsystem based on the parameters supplied.
+     *
      * @param params the test parameters
+     * @return JSON representation
      */
     JsonNode flowTest(Optional<JsonNode> params);
 

@@ -54,6 +54,7 @@ public class CompletedBatchOperation implements BatchOperationResult<FlowRule> {
      *
      * @param success  indicates whether the completion is successful.
      * @param failures set of any failures encountered
+     * @param deviceId device id
      */
     public CompletedBatchOperation(boolean success, Set<? extends FlowRule> failures,
                                    DeviceId deviceId) {

@@ -10,6 +10,8 @@ public interface DatabaseService {
     /**
      * Creates a ConsistentMap.
      *
+     * @param <K> Key type
+     * @param <V> value type
      * @param name map name
      * @param serializer serializer to use for serializing keys and values.
      * @return consistent map.