Change access modifier for readAdvise in MMapDirectory

Signed-off-by: Navneet Verma <navneev@amazon.com>

Author: navneet1v

lucene/CHANGES.txt

@@ -236,6 +236,8 @@ API Changes
 * GITHUB#15803: Add ReaderUtil#partitionByLeaf to partition doc IDs from
   ScoreDoc hits by leaf reader. (Zihan Xu)
 
+* GITHUB#15892: Change access modifier for readAdvise in MMapDirectory (Navneet Verma)
+
 New Features
 ---------------------
 

lucene/core/src/java/org/apache/lucene/store/MMapDirectory.java

@@ -169,7 +169,7 @@ public class MMapDirectory extends FSDirectory {
         return Optional.of(Constants.DEFAULT_READADVICE);
       };
 
-  private BiFunction<String, IOContext, Optional<ReadAdvice>> readAdvice =
+  protected BiFunction<String, IOContext, Optional<ReadAdvice>> readAdvice =
       (_, _) -> Optional.empty();
 
   private BiPredicate<String, IOContext> preload = NO_FILES;