@Override
  public Optional<Bytes> getFlatStorageValueByStorageSlotKey(
      final Supplier<Optional<Bytes>> worldStateRootHashSupplier,
      final Supplier<Optional<Hash>> storageRootSupplier,
      final NodeLoader nodeLoader,
      final Hash accountHash,
      final StorageSlotKey storageSlotKey,
      final SegmentedKeyValueStorage storage) {
    getStorageValueCounter.inc();
    Optional<Bytes> response =
        storage
            .get(
                ACCOUNT_STORAGE_STORAGE,
                Bytes.concatenate(accountHash, storageSlotKey.getSlotHash()).toArrayUnsafe())
            .map(Bytes::wrap);
    if (response.isEmpty()) {
      final Optional<Hash> storageRoot = storageRootSupplier.get();
      final Optional<Bytes> worldStateRootHash = worldStateRootHashSupplier.get();
      if (storageRoot.isPresent() && worldStateRootHash.isPresent()) {
        response =
            new StoredMerklePatriciaTrie<>(
                    new StoredNodeFactory<>(nodeLoader, Function.identity(), Function.identity()),
                    storageRoot.get())
                .get(storageSlotKey.getSlotHash())
                .map(bytes -> Bytes32.leftPad(RLP.decodeValue(bytes)));
        if (response.isEmpty()) getStorageValueMissingMerkleTrieCounter.inc();
        else getStorageValueMerkleTrieCounter.inc();
      }
    } else {
      getStorageValueFlatDatabaseCounter.inc();
    }
    return response;
  }
This class represents a strategy for reading data from a partial flat database. It extends the
FlatDbReaderStrategy and provides additional functionality for reading data from a merkle trie.
If data is missing in the flat database, this strategy falls back to the merkle trie to retrieve
the data. It adds a fallback mechanism for the `getAccount` and `getStorageValueByStorageSlotKey`
methods, which checks if the data is present in the flat database, and if not, queries the merkle
trie
ethereum/core/src/main/java/org/hyperledger/besu/ethereum/trie/pathbased/bonsai/storage/flat/BonsaiPartialFlatDbStrategy.java