@Override
  protected void prioritizeTransaction(final PendingTransaction pendingTransaction) {
    // check if it's in static or dynamic range
    final String kind;
    if (isInStaticRange(pendingTransaction.getTransaction(), baseFee)) {
      kind = "static";
      prioritizedTransactionsStaticRange.add(pendingTransaction);
    } else {
      kind = "dynamic";
      prioritizedTransactionsDynamicRange.add(pendingTransaction);
    }
    LOG.atTrace()
        .setMessage("Adding {} to pending transactions, range type {}")
        .addArgument(pendingTransaction::toTraceLog)
        .addArgument(kind)
        .log();
  }
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