Grant custom advancement upon emptying a filled composter

hey so Im working on a custom gamemode where I have custom advancements etc. and I want to create an advancement called "Composting". the player should be granted this advancement upon emptying a filled composter. the player shouldnt have to collect the bone meal (if possible) but rather just empty it. 
I could cheat this a little bit by just using the trigger "inventory_changed" but players are able to obtain bone meal without using a composter which is why I want to avoid using that trigger.
this is the advancement json. i tried everything but I just dont know what trigger I can use (if there even is any that makes this work):
{
  "parent": "skyquest:overworld/how_to_plant_seeds",
  "display": {
    "icon": {
      "id": "minecraft:composter",
      "count": 1
    },
    "title": "Composting",
    "description": "Collect Bone Meal from a Composter",
    "frame": "task",
    "show_toast": true,
    "announce_to_chat": true
  },
  "criteria": {
    "collect_bone_meal_from_composter": {
      "trigger": "minecraft:help_pls",
      }
    },
  "rewards": {
    "function": "skyquest:give/loot/advancement/composting"
  }
}