@Override
  public IMemMNode getAsMNode() {
    return this;
  }
The basic memory occupied by any BasicMNode object.

<ol>
  <li>object header, 8B
  <li>node attributes
      <ol>
        <li>basicMNodeInfo reference, 8B
        <li>parent reference, 8B
        <li>fullPath reference, 8B
      </ol>
  <li>MapEntry in parent
      <ol>
        <li>key reference, 8B
        <li>value reference, 8B
        <li>entry size, see ConcurrentHashMap.Node, 28
      </ol>
</ol>
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/impl/mem/mnode/basic/BasicMNode.java