private void cancelQueries() {
    synchronized (runningQueries) {
      isCancelled.set(true);
      runningQueries.forEach(f -> f.cancel(true));
      pivotBlockQueriesByPeerId.values().forEach(EthTask::cancel);
    }
  }
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