@Override
  public long calculateStorageRefundAmount(
      final UInt256 newValue,
      final Supplier<UInt256> currentValue,
      final Supplier<UInt256> originalValue) {
    return newValue.isZero() && !currentValue.get().isZero() ? STORAGE_RESET_REFUND_AMOUNT : 0L;
  }
Returns the base gas cost for external code accesses.

@return the base gas cost for external code accesses
evm/src/main/java/org/hyperledger/besu/evm/gascalculator/FrontierGasCalculator.java