When you find a chest loot in shipwrecks, it doesn't generate moss blocks inside of it. This isn't in parity with Java.

Step to Reproduce
1. Find a shipwreck, and find a supply chest.
2. Pick block it (and hold down ctrl on the keyboard).
3. Place it somewhere and break it (make sure to repeat this process too).
---> It doesn't generate with Moss Block.

Alternatively, you can check inside the loot tables json files to see if they have moss block listed there.