Using generics constrains to manipulate base class properties

Main.kt

import java.time.LocalDateTime
import java.util.UUID.randomUUID

abstract class EntityBase {
    lateinit var id: String
    lateinit var createAt: LocalDateTime
    lateinit var lastUpdateAt: LocalDateTime
}

class Person(val name: String) : EntityBase()

interface Repository<T> { fun save(entity: T) : T }

class RepositoryImpl<T> : Repository<T> where T: EntityBase { //EntityBase Constraint
    override fun save(entity: T): T {
        val now = LocalDateTime.now()
        
        //EntityBase properties manipulation
        entity.apply {
            id = randomUUID().toString()
            createAt = now
            lastUpdateAt = now 
        }
        
        //save implementation...
        
        return entity
    }
}