Add CHANGELOG entry and spotless results

Signed-off-by: Atri Sharma <atri.jiit@gmail.com>

Author: atris

CHANGELOG.md

@@ -99,6 +99,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### Fixed
 - Fix flaky tests in CloseIndexIT by addressing cluster state synchronization issues ([#18878](https://github.com/opensearch-project/OpenSearch/issues/18878))
+- Fix flaky ExistsQueryBuilderTests.testToQuery ([#18274](https://github.com/opensearch-project/OpenSearch/issues/18274))
 - Add task cancellation checks in aggregators ([#18426](https://github.com/opensearch-project/OpenSearch/pull/18426))
 - Fix concurrent timings in profiler ([#18540](https://github.com/opensearch-project/OpenSearch/pull/18540))
 - Fix regex query from query string query to work with field alias ([#18215](https://github.com/opensearch-project/OpenSearch/issues/18215))

server/src/test/java/org/opensearch/index/query/ExistsQueryBuilderTests.java

@@ -93,8 +93,9 @@ protected ExistsQueryBuilder doCreateTestQueryBuilder() {
         }
         // Avoid patterns that would match the derived field "raw.derived_keyword"
         // This includes "raw", "raw*", "raw.xxx", "r*", "ra*", etc.
-        if (fieldPattern.equals("raw") || fieldPattern.startsWith("raw") || 
-            (fieldPattern.contains("*") && "raw.derived_keyword".startsWith(fieldPattern.replace("*", "")))) {
+        if (fieldPattern.equals("raw")
+            || fieldPattern.startsWith("raw")
+            || (fieldPattern.contains("*") && "raw.derived_keyword".startsWith(fieldPattern.replace("*", "")))) {
             fieldPattern = TEXT_FIELD_NAME;
         }
         return new ExistsQueryBuilder(fieldPattern);