When using the AsyncStructureGenerateEvent with a BlockTransformer, no matter what the transformer does the TrialSpawner loses its data when being generated initially.

Got: 

{x: -307, y: -10, spawn_data: {entity: {}}, z: -223, id: "minecraft:trial_spawner"}

Expected:

{normal_config: "minecraft:trial_chamber/melee/husk/normal", x: -307, y: -10, spawn_data: {entity: {id: "minecraft:husk"}}, z: -223, id: "minecraft:trial_spawner", ominous_config: "minecraft:trial_chamber/melee/husk/ominous"}

How to reproduce:
1. Install the test plugin (attached below + source code)
2. Locate a trial chamber
3. Go to the trial chamber and find a trial spawner
4. See that all trail spawners are empty

(Seed -5258296247174339473)

Bug seems to have been introduce in 1.21.1 as the old 1.21.0 build worked fine:
Works: 4204-Spigot-146439e-a1d2cd1 (MC: 1.21) (Implementing API version 1.21-R0.1-SNAPSHOT)
Doesn't work: 4344-Spigot-a759b62-19bf846 (MC: 1.21.1) (Implementing API version 1.21.1-R0.1-SNAPSHOT)