Minecraft wiki entry for Container_entity, associated text:  Items: List of items.
An item, including the Slot tag.
Tags common to all items[show]
 LootTable: Optional. Loot table to be used to fill the entity's container when it is next opened, or the items are otherwise interacted with. Both LootTable and LootTableSeed are removed once the items have been generated.
 LootTableSeed: Optional. Seed for generating the loot table. 0 or omitted uses a random seed.