@VisibleForTesting
  protected void broadcastBlockRange() {
    blockchain
        .getEarliestBlockNumber()
        .ifPresentOrElse(
            earliestBlockNumber -> {
              BlockHeader chainHeader = blockchain.getChainHeadHeader();
              broadcastBlockRange(
                  earliestBlockNumber, chainHeader.getNumber(), chainHeader.getHash());
            },
            () -> {
              BlockHeader genesisBlock = blockchain.getGenesisBlockHeader();
              broadcastBlockRange(
                  genesisBlock.getNumber(), genesisBlock.getNumber(), genesisBlock.getHash());
            });
  }
Broadcasts a block range update message to all connected peers that support the
BLOCK_RANGE_UPDATE protocol. This method is used to inform peers about the range of blocks
available, from the earliest to the latest. If the earliest block number is not available, the
genesis block number is used as a fallback.
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/BlockRangeBroadcaster.java