{
  "1. Command cooldown": 0.0,
  "2. List of weapons": [{
      "Weapon shortname": "Multiple Grenade Launcher",
      "Ammo shortname": "40mm HE Grenade",
      "Minimal ammo that be given": 10,
      "Maximal ammo that be given": 100
    },
    {
      "Weapon shortname": "Multiple Grenade Launcher",
      "Ammo shortname": "40mm Shotgun Round",
      "Minimal ammo that be given": 10,
      "Maximal ammo that be given": 100
    },
    {
      "Weapon shortname": "Multiple Grenade Launcher",
      "Ammo shortname": "40mm Smoke Grenade",
      "Minimal ammo that be given": 10,
      "Maximal ammo that be given": 100
    }
  ]
}

private ConfigData GetDefaultConfig() {
  return new ConfigData {
    cooldown = 0,
      list = new List < ConfigData.OWeapon > {
        new ConfigData.OWeapon {
          weaponName = "MultipleGrenadeLauncher",
            ammoName = "40mmHEGrenade",
            minAmmo = 10,
            maxAmmo = 100
        },
        new ConfigData.OWeapon {
          weaponName = "MultipleGrenadeLauncher",
            ammoName = "40mmShotgunRound",
            minAmmo = 10,
            maxAmmo = 100
        },
        new ConfigData.OWeapon {
          weaponName = "MultipleGrenadeLauncher",
            ammoName = "40mmSmokeGrenade",
            minAmmo = 10,
            maxAmmo = 100
        }
      }
  };
}

No weapons will come out

Because its not shortnames... You can find list of shortnames here

https://umod.org/documentation/games/rust/definitions#items