LootInj

{
  // All fields are optional except `targets`

  // A loot table id or list of ids to modify
  "targets": [
    "minecraft:blocks/dirt"
  ],

  // A list of loot pools to add
  "pools": [
    {
      "rolls": 1,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "minecraft:diamond"
        }
      ]
    }
  ],

  // A loot function or list of functions to add to the whole table
  "modifier": {
    "count": 2,
    "function": "minecraft:set_count"
  },

  // Modify all existing pools
  // Requires some extra processing so only include if you need to modify pools
  "modify_pools": {
    // Again, all fields are optional

    // A list of entries to add to the pool
    "entries": [
      {
        "type": "minecraft:item",
        "name": "minecraft:gold_ingot"
      }
    ],
    
    // A loot condition or list of conditions to add to the whole pool
    "condition": {
      "type": "minecraft:survives_explosion"
    },

    // A loot function or list of functions to add to the whole pool
    "modifier": {
      "count": 3,
      "function": "minecraft:set_count"
    }

  }

}

{
  // All fields are optional except `targets`

  // A loot table id or list of ids to modify
  "targets": [
    "minecraft:blocks/dirt"
  ],

  // A list of loot pools to add
  "pools": [
    {
      "rolls": 1,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "minecraft:diamond"
        }
      ]
    }
  ],

  // A list of loot functions to add to the whole table
  "functions": [
    {
      "count": 2,
      "function": "minecraft:set_count"
    }
  ],

  // Modify all existing pools
  // Requires some extra processing so only include if you need to modify pools
  "modify_pools": {
    // Again, all fields are optional

    // A list of entries to add to the pool
    "entries": [
      {
        "type": "minecraft:item",
        "name": "minecraft:gold_ingot"
      }
    ],
    
    // A list of loot condition to add to the whole pool
    "conditions": [
      {
        "type": "minecraft:survives_explosion"
      }
    ],

    // A list of loot functions to add to the whole pool
    "functions": [
      {
        "count": 3,
        "function": "minecraft:set_count"
      }
    ]

  }

}

For use in a mod, install and JiJ it from the Modrinth maven.

# gradle.properties
lootinj_version=1.0.4+mc26.3

// build.gradle
repositories {
    exclusiveContent {
        forRepository {
            maven {
                name = "Modrinth"
                url = "https://api.modrinth.com/maven"
            }
        }
        filter {
            includeGroup "maven.modrinth"
        }
    }
}

dependencies {
    // ...
    implementation include("maven.modrinth:lootinj:${project.lootinj_version}")
}