public Range<Long> getBlockPropagationRange() {
    return blockPropagationRange;
  }
The range of block numbers (relative to the current chain head and the best network block) that
are considered appropriate to import as new blocks are announced on the network.

@return the range of blocks considered valid to import from the network, relative to the
    current chain head.
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/SynchronizerConfiguration.java