private InsertNode parse(final ByteBuffer buffer) {
    final PlanNode node = WALEntry.deserializeForConsensus(buffer);
    if (node instanceof InsertNode) {
      return (InsertNode) node;
    } else {
      return null;
    }
  }
This cache is used by {@link WALEntryPosition}.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/wal/utils/WALInsertNodeCache.java