@Override
  public void manageBlockAdded(final BlockHeader blockHeader) {
    blockHeader.getBaseFee().ifPresent(this::updateBaseFee);
  }
See this post for an explainer about these data structures:
https://hackmd.io/@adietrichs/1559-transaction-sorting
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/transactions/sorter/BaseFeePendingTransactionsSorter.java