Changed CommentManagementAPIImpl

changed returning null into response ok.

components/application-mgt/org.wso2.carbon.device.application.mgt.store.api/src/main/java/org/wso2/carbon/device/application/mgt/store/api/services/impl/CommentManagementAPIImpl.java

@@ -73,7 +73,7 @@ public class CommentManagementAPIImpl implements CommentManagementAPI {
             return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(" Internal server error occurs")
                 .build();
         }
-        return null;
+        return Response.status(Response.Status.OK).build();
     }
 
     @Override