[
  {
    "type": "item_group",
    "subtype": "collection",
    "id": "structural_spur_drops",
    "entries": [
      { "item": "rock", "count": [ 10, 22 ] },
      { "item": "scrap", "count": [ 10, 12 ] },
      { "item": "rebar", "count": [ 3, 8 ] }
    ]
  },
  {
    "type": "item_group",
    "subtype": "collection",
    "id": "shrapnel_swarm_drops",
    "entries": [ { "item": "shrapnel", "count": [ 3, 7 ] } ]
  }
]
