How can I make a smithing table recipe that yields a named item?

I am trying to make a datapack where you can combine a turtle shell and a netherite ingot in a smithing table to get a turtle shell with knockback resistance and armor toughness. I have figured out the whole smithing table situation, but I cannot get it to yield an item with attributes. Here is a snip of what it looks like in the smithing table and a snip of the code.

{
  "type": "minecraft:smithing",
  "base": {
    "item": "minecraft:turtle_helmet"
  },
  "addition": {
    "item": "minecraft:netherite_ingot"
  },
  "result": {
    "item": "minecraft:turtle_helmet"
    }
  }
}