@Override
  protected PendingTransaction getEvictable() {
    return orderByFee.first();
  }
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