Assert we have a reference to the request

Author: nicktindall

modules/repository-gcs/src/main/java/org/elasticsearch/repositories/gcs/GoogleCloudStorageHttpStatsCollector.java

@@ -62,6 +62,7 @@ public void process(HttpResponse response, HttpContext context) {
         }
         final HttpClientContext clientContext = HttpClientContext.adapt(context);
         final HttpRequest request = clientContext.getRequest();
+        assert request != null;
         for (HttpRequestTracker tracker : trackers) {
             if (tracker.track(request, gcsOperationStats)) {
                 return;