I recently noticed that containers with attached LootTables in structures no longer store the LootTableSeed attribute, which results in non deterministic container content(when recreating a world with the same seed and reopening the same chest its contents will be different, which isn't vanilla behaviour).

I first noticed the bug in 1.20.2 builds for paper but the current spigot and craftbukkit builds show the same behaviour, while the vanilla client/server still stores the LootTableSeed. So i would assume the bug was introduced by bukkit/craftbukkit.

Steps to reproduce:

• generate a new world using the newest craftbukkit or spigot 1.20.2 jar
• find a structure with containers
• pick one container(without opening it)
• save the world
• open the corresponding region file and search for the container
• the container has the LootTable attribute attached, but is missing the LootTableSeed attribute

Alternatively:

• generate a new world using the newest craftbukkit or spigot 1.20.2 jar
• find a structure with containers
• pick one container
• open the container, write down its contents
• stop the server
• delete the corresponding region folder/file
• restart the server
• reopen the container, write down its contents
• compare the container content from both samples

When recreating these steps on a vanilla 1.20.2 server the LootTableSeed attribute is present.

For some additional context:
The bug was introduced to paper in https://github.com/PaperMC/paper/commit/4cdbb0c86c40f5ff93a9a7cdca3102636b35b6d4(1.20 build #204 still works, while 1.20 build #205 doesn't), so one of the merged changes will be its cause. I don't seem to be able to find old craftbukkit or spigot builds, so i'm unable to pin it down any further.