@Override
    public @Nullable Pair<ByteBuffer, InsertNode> load(@NonNull final WALEntryPosition key)
        throws Exception {
      return new Pair<>(key.read(), null);
    }
This cache is used by {@link WALEntryPosition}.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/wal/utils/WALInsertNodeCache.java