@Override
            public void handle(IAsyncResult<Void> result) {
                if (result.isSuccess()) {
                    updateDataVersion();
                }
                handler.handle(result);
            }
@see io.apiman.gateway.engine.async.IAsyncHandler#handle(java.lang.Object)
gateway/engine/es/src/main/java/io/apiman/gateway/engine/es/PollCachingEsRegistry.java