@Override
  public long gasRequirement(final Bytes input) {
    return gasCost;
  }
Create Istanbul AltBN128Add precompiled contract.

@param gasCalculator the gas calculator
@return the AltBN128Add precompiled contract
evm/src/main/java/org/hyperledger/besu/evm/precompile/AltBN128AddPrecompiledContract.java