{
  "type": "minecraft:random_selector",
  "config": {
    "default": "minecraft:birch_checked",
    "features": [
      {
        "chance": 0.2,
        "feature": "minecraft:spruce_checked"
      },
      {
        "chance": 0.4,
        "feature": "minecraft:oak_checked"
      }
    ]
  }
}