---

Goal: Prevent the item <minecraft:cobblestone> from dropping when <minecraft:stone> or <minecraft:cobblestone> is broken.

---

Here we're asking Dropt to match when either minecraft:stone or minecraft:cobblestone is broken and minecraft:cobblestone is dropped. The replace strategy tells Dropt that we want to replace any items that we've listed in the drop match section with drops selected from our pool. Since we've only added a single empty drop, the empty drop will always be selected.

---

ZenScript

import mods.dropt.Dropt;

Dropt.list("list_name")

  .add(Dropt.rule()
      .matchBlocks(["minecraft:stone", "minecraft:cobblestone"])
      .matchDrops([<minecraft:cobblestone>])
      .replaceStrategy("REPLACE_ITEMS")
      .addDrop(Dropt.drop())
  );

JSON

{
  "rules": [
    {
      "match": {
        "blocks": {
          "blocks": [
            "minecraft:stone",
            "minecraft:cobblestone"
          ]
        },
        "drops": {
          "drops": [
            "minecraft:cobblestone"
          ]
        }
      },
      "replaceStrategy": "REPLACE_ITEMS",
      "drops": [{}]
    }
  ]
}

DroptAPI

@SubscribeEvent
public void on(DroptLoadRulesEvent event) {

  List<IDroptRuleBuilder> list = new ArrayList<>();

  list.add(DroptAPI.rule()
      .matchBlocks(new String[]{
          "minecraft:stone",
          "minecraft:cobblestone"
      })
      .matchDrops(new String[]{
          "minecraft:cobblestone"
      })
      .replaceStrategy(EnumReplaceStrategy.REPLACE_ITEMS)
      .addDrops(new IDroptDropBuilder[]{
          DroptAPI.drop()
      })
  );

  ResourceLocation resourceLocation = new ResourceLocation("my_mod_id", "rule_list_name");
  int priority = 0;
  DroptAPI.registerRuleList(resourceLocation, priority, list);
}