@Override
  protected TransactionAddedResult canAdd(
      final PendingTransaction pendingTransaction, final int gap) {
    final var senderTxs = txsBySender.get(pendingTransaction.getSender());

    if (hasExpectedNonce(senderTxs, pendingTransaction, gap) && hasPriority(pendingTransaction)) {

      return TransactionAddedResult.ADDED;
    }

    return TransactionAddedResult.TRY_NEXT_LAYER;
  }
Holds the current set of executable pending transactions, that are candidate for inclusion on
next block. The pending transactions are kept sorted by paid fee descending.
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/transactions/layered/AbstractPrioritizedTransactions.java