public CompletableFuture<FastSyncState> confirmPivotBlock() {
    if (isStarted.compareAndSet(false, true)) {
      LOG.info(
          "Confirm pivot block {} with at least {} peers.", pivotBlockNumber, numberOfPeersToQuery);
      queryPeers(pivotBlockNumber);
    }

    return result;
  }
This task will query {@code numberOfPeersToQuery} peers for a particular block number. If any
peers disagree on the block at this number, the task fails with a {@code
ContestedPivotBlockException}. The task will succeed only if {@code numberOfPeersToQuery}
distinct peers all return matching block headers for the specified block number.
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/fastsync/PivotBlockConfirmer.java