DynamicallyMappable

Names the dynamic_dto discriminator a class stands for.

The name travels in the type_name attribute of the composite and is what turns a JSON payload back into one class rather than another. It is what SQL writes when it builds a value by hand - dynamic_dto('land_grant', jsonb_build_object(...)) - so it has to be stated rather than derived: the discriminator lives in the data, and a name derived from the class would change silently when the class was renamed, leaving every row written before that unreadable.

The class also has to be @Serializable; the payload is JSON and nothing else reads it.

@Serializable
@DynamicallyMappable("land_grant")
data class LandGrant(val province: String, val iugera: Int)