default Wei getOmmerReward(
      final Wei blockReward, final long blockNumber, final long ommerBlockNumber) {
    final long distance = blockNumber - ommerBlockNumber;
    return blockReward.subtract(blockReward.multiply(distance).divide(8));
  }
Get ommer reward in ${@link Wei}

@param blockReward reward of the block
@param blockNumber number of the block
@param ommerBlockNumber number of the block ommer
@return ommer reward
ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/BlockProcessor.java