Add changlog and address review comments

Signed-off-by: Shreyansh Ray <[email protected]>

Author: rayshrey

CHANGELOG.md

@@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Bump OpenSearch Core main branch to 3.0.0 ([#18039](https://github.com/opensearch-project/OpenSearch/pull/18039))
 - Update API of Message in index to add the timestamp for lag calculation in ingestion polling ([#17977](https://github.com/opensearch-project/OpenSearch/pull/17977/))
 - Enabled default throttling for all tasks submitted to cluster manager ([#17711](https://github.com/opensearch-project/OpenSearch/pull/17711))
+- Add composite directory factory ([#17988](https://github.com/opensearch-project/OpenSearch/pull/17988))
 
 ### Changed
 - Change the default max header size from 8KB to 16KB. ([#18024](https://github.com/opensearch-project/OpenSearch/pull/18024))

server/src/main/java/org/opensearch/index/IndexModule.java

@@ -822,14 +822,14 @@ private static IndexStorePlugin.DirectoryFactory getDirectoryFactory(
 
     private static IndexStorePlugin.CompositeDirectoryFactory getCompositeDirectoryFactory(
         final IndexSettings indexSettings,
-        final Map<String, IndexStorePlugin.CompositeDirectoryFactory> indexStoreFactories
+        final Map<String, IndexStorePlugin.CompositeDirectoryFactory> compositeDirectoryFactories
     ) {
         final String compositeStoreType = indexSettings.getValue(INDEX_COMPOSITE_STORE_TYPE_SETTING);
         final IndexStorePlugin.CompositeDirectoryFactory factory;
-        if (compositeStoreType.isEmpty() || indexStoreFactories.isEmpty()) {
+        if (compositeStoreType.isEmpty() || compositeDirectoryFactories.isEmpty()) {
             factory = DEFAULT_COMPOSITE_DIRECTORY_FACTORY;
         } else {
-            factory = indexStoreFactories.get(compositeStoreType);
+            factory = compositeDirectoryFactories.get(compositeStoreType);
             if (factory == null) {
                 throw new IllegalArgumentException("Unknown composite store type [" + compositeStoreType + "]");
             }