- GravityFlipRegion holds Name (String) + Box (Hytale AABB) + Enabled (boolean),
serialised through a BuilderCodec keyed on "Name"/"Box"/"Enabled".
- Validators.nonNull() applied to Name and Box (correct package is
com.hypixel.hytale.codec.validation.Validators, not codec.builder).
- Server jar 2026.03.26 uses com.hypixel.hytale.math.vector.Vector3d for Box.min/max
(NOT org.joml.Vector3d, which only appeared in newer builds).
- 3 JUnit 5 round-trip tests cover name/box/enabled, enabled=false, and empty name.
- testImplementation added for the Server artifact so codec encode/decode is
reachable from unit tests.