private CompletableFuture<List<BlockHeader>> pauseBriefly() {
    return ethScheduler.scheduleFutureTask(
        () -> completedFuture(emptyList()), RETRY_DELAY_DURATION);
  }
Pause after failing to get new range to prevent requesting new range headers in a tight loop.

@return a future that after the pause completes with an empty list.
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/range/SyncTargetRangeSource.java