@Override
  public void onBlockAdded(final BlockAddedEvent event) {
    if (isPoolEnabled.get()) {
      if (event.getEventType().equals(BlockAddedEvent.EventType.HEAD_ADVANCED)
          || event.getEventType().equals(BlockAddedEvent.EventType.CHAIN_REORG)) {

        blockAddedEventOrderedProcessor.submit(event);
      }
    }
  }
Maintains the set of pending transactions received from JSON-RPC or other nodes. Transactions are
removed automatically when they are included in a block on the canonical chain and re-added if a
re-org removes them from the canonical chain again.

<p>This class is safe for use across multiple threads.
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/transactions/TransactionPool.java