Allow system index warning in OpenSearchRestTestCase.refreshAllIndices (#14635)

* Allow system index warning

Signed-off-by: Craig Perkins <cwperx@amazon.com>

* Add to CHANGELOG

Signed-off-by: Craig Perkins <cwperx@amazon.com>

* Address code review comments

Signed-off-by: Craig Perkins <cwperx@amazon.com>

---------

Signed-off-by: Craig Perkins <cwperx@amazon.com>

Author: cwperks

CHANGELOG.md

@@ -36,6 +36,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Make the class CommunityIdProcessor final ([#14448](https://github.com/opensearch-project/OpenSearch/pull/14448))
 - Allow @InternalApi annotation on classes not meant to be constructed outside of the OpenSearch core ([#14575](https://github.com/opensearch-project/OpenSearch/pull/14575))
 - Add @InternalApi annotation to japicmp exclusions ([#14597](https://github.com/opensearch-project/OpenSearch/pull/14597))
+- Allow system index warning in OpenSearchRestTestCase.refreshAllIndices ([#14635](https://github.com/opensearch-project/OpenSearch/pull/14635))
 
 ### Deprecated
 

test/framework/src/main/java/org/opensearch/test/rest/OpenSearchRestTestCase.java

@@ -708,11 +708,15 @@ protected void refreshAllIndices() throws IOException {
         requestOptions.setWarningsHandler(warnings -> {
             if (warnings.isEmpty()) {
                 return false;
-            } else if (warnings.size() > 1) {
-                return true;
-            } else {
-                return warnings.get(0).startsWith("this request accesses system indices:") == false;
             }
+            boolean allSystemIndexWarnings = true;
+            for (String warning : warnings) {
+                if (!warning.startsWith("this request accesses system indices:")) {
+                    allSystemIndexWarnings = false;
+                    break;
+                }
+            }
+            return !allSystemIndexWarnings;
         });
         refreshRequest.setOptions(requestOptions);
         client().performRequest(refreshRequest);