    function setVcon(IERC20 _vcon) external onlyGovernor {
        vcon = _vcon;

        emit VconUpdate(_vcon);
    }
    IERC20 private immutable _vcon;
    ...
    constructor(address coreAddress) {
        ...
        _vcon = ICore(coreAddress).vcon();
        ...
    }
    function vcon() public view override returns (IERC20) {
        return _volt.vcon();
    }
