[Bug] u_spawn_item only spawn one item when the item group's subtype is "collection"

[PipeYume]

Describe the bug

The u_spawn_item function only spawns a single item when the item group's subtype is "collection," which is not what I expected. Upon reviewing all the mods, I noticed that every item group used by this method is of the "distribution" type.

It seems that u_spawn_item may not be suitable for handling item groups with the "collection" subtype.

Attach save file

None

Steps to reproduce

[
  {
    "type": "effect_on_condition",
    "id": "EOC_test_equip_items",
    "effect": { "u_spawn_item": "GROUP_test_equipment", "use_item_group": true, "force_equip": true, "flags": [ "UNBREAKABLE" ] }
  },
  {
    "type": "item_group",
    "id": "GROUP_test_equipment",
    "subtype": "collection",
    "entries": [
      { "item": "bodysuit_lycra", "variant": "superhero_suit_purple" },
      { "item": "mask_bal" },
      { "item": "long_patchwork_scarf", "prob": 50 }
    ]
  }
]

This will spawn only 1 item ("bodysuit_lycra")

Expected behavior

When the item group is "collection" type, spawn all the items with give probability inside it.

Screenshots

No response

Versions and configuration

0.G-6554-g1eb1b6fe88

Additional context

No response