public Optional<TransactionLocation> transactionLocationByHash(final Hash transactionHash) {
    return blockchain.getTransactionLocation(transactionHash);
  }
Helper method to return the transaction at the given index for the specified header, used by
getTransactionByBlock*AndIndex methods.

@param header The block header.
@param txIndex The index of the transaction to return.
@return The transaction at the specified location.
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/query/BlockchainQueries.java