Hibernate detached entity passed to persist error in Spring Boot in Kotlin using OneToOne with MapsId - spring

Question

I have the following entities in a fairly simple and straightforward Spring Boot application in Kotlin:
#Entity
class Target(
#Id #GeneratedValue var id: Long? = null,
// ... other stuff
)
#Entity
class Ruleset(
#OneToOne(fetch = FetchType.LAZY) #MapsId
var target: Target,
#Id #GeneratedValue var id: Long? = null,
// ... other stuff
)
And I have the following code to create them upon startup of a #Component:
#PostConstruct
#Transactional
fun init() {
val target = Target()
targetRepository.save(target)
val rule = Ruleset(target)
rulesetRepository.save(rule)
}
And when this runs I get the "detached entity passed to persist: com.mystuff.Target" error. I've used this approach in the past (see here: https://vladmihalcea.com/the-best-way-to-map-a-onetoone-relationship-with-jpa-and-hibernate/) without issue, although never in trying to create them at the same time in the same method. I've also tried using the entity passed back by the .save() call on the Target repository in the persist of the Ruleset object with no success.
I am able to fix this if I go back to the "normal" way of doing a OneToOne relationship:
#Entity
class Target(
#OneToOne(mappedBy = "target", cascade = [CascadeType.ALL],
fetch = FetchType.LAZY, optional = false)
var ruleset: Ruleset?
#Id #GeneratedValue var id: Long? = null
)
#Entity
class Ruleset(
#OneToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "target_id")
var target: Target,
#Id #GeneratedValue var id: Long? = null,
)
But this is annoying as it forces me to pass a null into the Target constructor and then update it immediately after creating the Ruleset. I can't figure out why the other, simpler approach doesn't work.