public Optional<Wei> accountBalance(final Address address, final long blockNumber) {
    final Hash blockHash = getBlockHashByNumber(blockNumber).orElse(Hash.EMPTY);

    return accountBalance(address, blockHash);
  }
Returns the balance of the given account at a specific block number.

@param address The address of the account being queried.
@param blockNumber The block number being queried.
@return The balance of the account in Wei.
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/query/BlockchainQueries.java