V0id's Smart Backpack contents lost

[bluelightning32]

Issue Description:

After logging out and logging back in, the contents of backpacks from the V0id's smart Backpacks mod are lost. The mod is storing the backpack contents in the ForgeCaps tag.

As this bug describes, the ForgeCaps are lost by Sponge:
#37

v0id backpack has an option to equip the backpack using a button. The equipped backpack does not show up any where in the inventory, but it can be accessed with a button. Equipped backpacks are not saved by invsync. So their contents are not lost but their contents are not transferred between servers either.

Steps to reproduce:

1. Get a backpack
2. Put something in it.
3. Log out.
4. Log back in and the contents are lost.

---

Affected Versions (Do not use "latest"):

• Minecraft: 1.11.2
• InvSync: InvSync-0.6.19.307-DEV.jar
• Sponge: spongeforge-1.12.2-2768-7.1.6-RC3616.jar
• Other related mods: V0id's Smart Backpacks-1.0.6.jar

Your most recent log or stack trace file where the issue was present:

Before logging out:

$ nbtutil --path 2e15e144-51b9-4f4b-a495-74dc0765a409.dat --printtree
...
   | + 6 entries
   | | + Count: 1
   | | + Slot: 1
   | | + Damage: 0
   | | + id: v0idssmartbackpacks:backpack
   | | + ForgeCaps: 2 entries
   | | | + astralsorcery:cap_item_amulet_holder: 2 entries
   | | | | + AS_Amulet_HolderLeast: -6587230391593753591
   | | | | + AS_Amulet_HolderMost: 3320807983800733515
   | | | + Parent: 5 entries
   | | |   + color: 0
   | | |   + energy: 0
   | | |   + maxEnergy: 0
   | | |   + inventory: 2 entries
   | | |   | + Size: 18
   | | |   | + Items: 1 entry
   | | |   |   + 6 entries
   | | |   |     + Count: 1
   | | |   |     + Damage: 12
   | | |   |     + Slot: 0
   | | |   |     + id: minecraft:iron_pickaxe
   | | |   |     + ForgeCaps: 1 entry
   | | |   |     | + astralsorcery:cap_item_amulet_holder: 0 entries
   | | |   |     + tag: 1 entry
   | | |   |       + pickletweaks: 1 entry
   | | |   |         + BlocksBroken: 17
   | | |   + upgrades: 2 entries
   | | |     + Size: 5
   | | |     + Items: 0 entries
   | | + tag: 2 entries
   | |   + backpack_tag: 4 entries
   | |   | + color: 0
   | |   | + energy: 0
   | |   | + energyMax: 0
   | |   | + upgrades: 2 entries
   | |   |   + Size: 5
   | |   |   + Items: 0 entries
   | |   + vsb:nbtItemHandler: 2 entries
   | |     + Size: 18
   | |     + Items: 1 entry
   | |       + 6 entries
   | |         + Count: 1
   | |         + Damage: 12
   | |         + Slot: 0
   | |         + id: minecraft:iron_pickaxe
   | |         + ForgeCaps: 1 entry
   | |         | + astralsorcery:cap_item_amulet_holder: 0 entries
   | |         + tag: 1 entry
   | |           + pickletweaks: 1 entry
   | |             + BlocksBroken: 17
...

After logging out and back in the ForgeCaps are lost:

$ nbtutil --path 2e15e144-51b9-4f4b-a495-74dc0765a409.dat --printtree
...
   + Inventory: 3 entries
   | + 6 entries
   | | + Count: 1
   | | + Slot: 1
   | | + Damage: 0
   | | + id: v0idssmartbackpacks:backpack
   | | + ForgeCaps: 2 entries
   | | | + astralsorcery:cap_item_amulet_holder: 2 entries
   | | | | + AS_Amulet_HolderLeast: -6587230391593753591
   | | | | + AS_Amulet_HolderMost: 3320807983800733515
   | | | + Parent: 5 entries
   | | |   + color: 0
   | | |   + energy: 0
   | | |   + maxEnergy: 0
   | | |   + inventory: 2 entries
   | | |   | + Size: 18
   | | |   | + Items: 0 entries
   | | |   + upgrades: 2 entries
   | | |     + Size: 5
   | | |     + Items: 0 entries
   | | + tag: 2 entries
   | |   + backpack_tag: 4 entries
   | |   | + color: 0
   | |   | + energy: 0
   | |   | + energyMax: 0
   | |   | + upgrades: 2 entries
   | |   |   + Size: 5
   | |   |   + Items: 0 entries
   | |   + vsb:nbtItemHandler: 2 entries
   | |     + Size: 18
   | |     + Items: 1 entry
   | |       + 6 entries
   | |         + Count: 1
   | |         + Damage: 12
   | |         + Slot: 0
   | |         + id: minecraft:iron_pickaxe
   | |         + ForgeCaps: 1 entry
   | |         | + astralsorcery:cap_item_amulet_holder: 0 entries
   | |         + tag: 1 entry
   | |           + pickletweaks: 1 entry
   | |             + BlocksBroken: 17
...

[bluelightning32]

If I put the v0id backpack inside of an Immersive Engineering Wooden Storage Crate, the void backpack's inventory is saved and restored correctly:

[22:54:49] [Server thread/INFO] [invsync]: {"mod.solcarrot":{"data":["harvestcraft:ryeitem@0","harvestcraft:delightedmealitem@0","harvestcraft:plumitem@0","harvestcraft:pearitem@0","minecraft:rotten_flesh@0","integrateddynamics:menril_berries@0","natura:edibles@4"]},"potion_effects":{"data":[]},"mod.cyclicmagic":{"crafting_capability":false,"inventory":[],"inventory_capability":false},"mod.baubles":{"data":[]},"mod.spiceoflife":{"data":{"spiceoflifeHistory":{"History":{"Foods":[{"WorldTime":63555819,"Hunger":2,"PlayerTime":55135,"Saturation":0.2,"id":"integrateddynamics:menril_berries","Count":14,"Damage":0},{"WorldTime":63555829,"Hunger":2,"PlayerTime":55145,"Saturation":0.2,"id":"integrateddynamics:menril_berries","Count":13,"Damage":0},{"WorldTime":63555839,"Hunger":2,"PlayerTime":55155,"Saturation":0.2,"id":"integrateddynamics:menril_berries","Count":12,"Damage":0},{"WorldTime":63567955,"Hunger":2,"PlayerTime":67271,"Saturation":0.2,"id":"integrateddynamics:menril_berries","Count":9,"Damage":0},{"WorldTime":63577112,"Hunger":1,"PlayerTime":76428,"Saturation":0.05,"id":"harvestcraft:plumitem","Count":1,"Damage":0},{"WorldTime":63578153,"Hunger":1,"PlayerTime":77469,"Saturation":0.1,"id":"natura:edibles","Count":9,"Damage":4}]}}}},"game_mode":{"data":"minecraft:survival"},"health":{"data":20.0},"ender_chest":{"data":[]},"inventory":{"selectedSlot":0,"inventory":[{"slot":0,"stack":{"ContentVersion":1,"ItemType":"minecraft:iron_pickaxe","Count":1,"UnsafeDamage":7,"UnsafeData":{"pickletweaks":{"BlocksBroken":11}}}},{"slot":1,"stack":{"ContentVersion":1,"ItemType":"immersiveengineering:wooden_device0","Count":1,"UnsafeDamage":0,"UnsafeData":{"inventory":[{"Slot":0,"id":"undergroundbiomes:sedimentary_stone","Count":1,"Damage":5},{"Slot":1,"ForgeCaps":{"Parent":{"maxEnergy":0,"color":0,"inventory":{"Size":18,"Items":[{"Slot":0,"id":"minecraft:leaves","Count":1,"Damage":3}]},"upgrades":{"Size":5,"Items":[]},"energy":0},"astralsorcery:cap_item_amulet_holder":{"AS_Amulet_HolderLeast":-6587230391593753591,"AS_Amulet_HolderMost":3320807983800733515}},"id":"v0idssmartbackpacks:backpack","Count":1,"tag":{"backpack_tag":{"color":0,"upgrades":{"Size":5,"Items":[]},"energyMax":0,"energy":0},"vsb:nbtItemHandler":{"Size":18,"Items":[{"Slot":0,"id":"minecraft:leaves","Count":1,"Damage":3}]}},"Damage":0}]}}},{"slot":36,"stack":{"ContentVersion":1,"ItemType":"minecraft:iron_boots","Count":1,"UnsafeDamage":189,"UnsafeData":{"ForgeCaps":{"astralsorcery:cap_item_amulet_holder":{"AS_Amulet_HolderLeast":-6587230391593753591,"AS_Amulet_HolderMost":3320807983800733515}}}}},{"slot":37,"stack":{"ContentVersion":1,"ItemType":"minecraft:iron_leggings","Count":1,"UnsafeDamage":163,"UnsafeData":{"ench":[{"lvl":2,"id":34}],"ForgeCaps":{"astralsorcery:cap_item_amulet_holder":{"AS_Amulet_HolderLeast":-6587230391593753591,"AS_Amulet_HolderMost":3320807983800733515}}}}}]},"experience":{"experience_since_level":24,"experience_level":11},"version":1,"hunger":{"saturation":0.0,"food_level":10}}