anchor.diff:            ${concatStringsSep "\n" (map (s: "MACVLAN=${s}") def.macvlan)}
             ${concatStringsSep "\n" (map (s: "VXLAN=${s}") def.vxlan)}
             ${concatStringsSep "\n" (map (s: "Tunnel=${s}") def.tunnel)}
  +          ${concatStringsSep "\n" (map (s: "Xfrm=${s}") def.xfrm)}
   
             ${optionalString (def.dhcpConfig != { }) ''
               [DHCP]
  
positive.code:       '';
      };
  
      addresses = mkOption {
        default = [ ];
        type = with types; listOf (submodule addressOptions);
  
negative.code:       '';
      };
  
      xfrmConfig = mkOption {
        default = {};
        example = { InterfaceId = 1; };
        type = types.addCheck (types.attrsOf unitOption) checkXfrm;
        description = ''
          Each attribute in this set specifies an option in the
          <literal>[Xfrm]</literal> section of the unit.  See
          <citerefentry><refentrytitle>systemd.netdev</refentrytitle>
          <manvolnum>5</manvolnum></citerefentry> for details.
        '';
      };
  
    };
  
    addressOptions = {
  