How to use

getExtraData

method

in

org.ethereum.config.BlockchainConfig

@Override
public byte[] getExtraData(byte[] minerExtraData, long blockNumber) {
  return parent.getExtraData(minerExtraData, blockNumber);
}

public synchronized Block createNewBlock(Block parent, List<Transaction> txs, List<BlockHeader> uncles, long time) {
  final long blockNumber = parent.getNumber() + 1;
  final byte[] extraData = config.getBlockchainConfig().getConfigForBlock(blockNumber).getExtraData(minerExtraData, blockNumber);