public Optional<UInt256> storageAt(
      final Address address, final UInt256 storageIndex, final Hash blockHash) {
    return fromAccount(
        address, blockHash, account -> account.getStorageValue(storageIndex), UInt256.ZERO);
  }
Determines the block header for the address associated with this storage index.

@param address The address of the account that owns the storage being queried.
@param storageIndex The storage index whose value is being retrieved.
@param blockHash The blockHash that is being queried.
@return The value at the storage index being queried.
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/query/BlockchainQueries.java