How do you add tags to loot drops?

I want mobs to drop a tnt item that has a custom tag "explosion_item". My current loot table json just drops a default tnt item:
  "type": "minecraft:entity",
  "pools": [
    {
      "rolls": 1,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "tnt",
          "functions": []
        }
      ],
      "functions": [],
      "conditions": []
    }
  ],
  "random_sequence": "minecraft:entities/cow"
}```