private boolean validateExtraData(final Bytes extraData) {
    if (extraData.size() > maxExtraDataBytes) {
      LOG.info(
          "Invalid block header: extra data field length {} is greater {}",
          extraData.size(),
          maxExtraDataBytes);
      return false;
    }

    return true;
  }
Responsible for ensuring the extra data fields in the header contain the appropriate number of
bytes.
ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/headervalidationrules/ExtraDataMaxLengthValidationRule.java