@Override
      public boolean accept(File dir, String name) {
        // If not segmented, log name is log_current
        // index name has the format of <offset>_index, for example 0_index, 265_index
        // In this case, input parameter logSegmentName == ""
        if (logSegmentName.toString().isEmpty()) {
          return name.endsWith(IndexSegment.INDEX_SEGMENT_FILE_NAME_SUFFIX);
        } else {
          return name.startsWith(logSegmentName.toString() + BlobStore.SEPARATOR) && name.endsWith(
              IndexSegment.INDEX_SEGMENT_FILE_NAME_SUFFIX);
        }
      }
Gets the list of {@link IndexSegment} files that refer to the log segment with name {@code logSegmentName}.
@param dataDir the directory where the index files are.
@param logSegmentName the name of the log segment whose index segment files are required.
@return the list of {@link IndexSegment} files that refer to the log segment with name {@code logSegmentName}.
ambry-store/src/main/java/com/github/ambry/store/PersistentIndex.java