Undyed Shulker Box has incorrect damage value in the creative inventory

When generating creative inventory json data to update my server (I'm a 3rd-party developer), I observed that the damage value for Undyed Shulker Box is wrong in the creative inventory.
```
{
"id": 205,
"damage": 16
}
```

The damage value 16 should be impossible since shulker box is a block, which means it should have a highest damage value of 15.
I believe this should correctly be 0, not 16.

The difference can be seen in-game by doing the following:

• Get a shulker box from the creative inventory

• Place and mine a shulker box. Put the mined shulker box in the hotbar.

• Equip the mined shulker box, then equip the creative one. You'll notice the player does the equip-item animation.

• Now do the same with 2 mined shulker boxes. No animation because they are identical.