public static BlobGas calculateExcessBlobGasForParent(
      final ProtocolSpec protocolSpec, final BlockHeader parentHeader) {
    // Blob Data Excess
    long headerExcess =
        protocolSpec
            .getGasLimitCalculator()
            .computeExcessBlobGas(
                parentHeader.getExcessBlobGas().map(BlobGas::toLong).orElse(0L),
                parentHeader.getBlobGasUsed().orElse(0L),
                parentHeader.getBaseFee().orElse(Wei.ZERO).toLong());
    return BlobGas.of(headerExcess);
  }
Calculates the excess blob gas for a parent block header.

@param protocolSpec The protocol specification of the current block.
@param parentHeader The parent block header.
@return The excess blob gas.
ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/feemarket/ExcessBlobGasCalculator.java