public CompletableFuture<Void> setEnabled() {
    if (!isEnabled()) {
      pendingTransactions = pendingTransactionsSupplier.get();
      pendingTransactionsListenersProxy.subscribe();
      isPoolEnabled.set(true);
      subscribeConnectId =
          OptionalLong.of(ethContext.getEthPeers().subscribeConnect(this::handleConnect));
      return saveRestoreManager
          .loadFromDisk()
          .exceptionally(
              t -> {
                LOG.error("Error while restoring transaction pool from disk", t);
                return null;
              });
    }
    return CompletableFuture.completedFuture(null);
  }
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