private Node<V> load() {
    if (loaded == null) {
      loaded =
          nodeFactory
              .retrieve(location, hash)
              .orElseThrow(
                  () ->
                      new MerkleTrieException(
                          "Unable to load trie node value for hash "
                              + hash
                              + " location "
                              + location,
                          hash,
                          location));
    }

    return loaded;
  }
Marks the node as being modified (needs to be persisted);
ethereum/trie/src/main/java/org/hyperledger/besu/ethereum/trie/StoredNode.java