Spring Boot - Entity With Kotlin List<Enum> Not Booting - spring

Question

I have been helping my team upgrade our Maven/SpringBoot/Kotlin project from Spring-Boot 2.7.5 to Spring-Boot 3.0.0. However, an issue on startup is preventing us from progressing. This has not been an issue before Spring-Boot 3.0.0.
Upon booting the application, I receive the following stack trace:
org.springframework.context.ApplicationContextException: Unable to start web server
...
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jpaSharedEM_entityManagerFactory': Cannot resolve reference to bean 'entityManagerFactory' while setting constructor argument
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: class sun.reflect.generics.reflectiveObjects.WildcardTypeImpl cannot be cast to class java.lang.reflect.ParameterizedType (sun.reflect.generics.reflectiveObjects.WildcardTypeImpl and java.lang.reflect.ParameterizedType are in module java.base of loader 'bootstrap')
After spending a day checking configurations and isolating the problem, we were left with one entity in our application, where we were still having the issue. We then started removing fields from the entity, until the application was able to run. The field we removed was a kotlin.collections.List of type Interaction, an enum class that we had defined for the application.
In order to ensure privacy, here is an isolated slice of the application MVC that will replicate this issue:
package com.example.adminapp.adminauth.persistence
import com.fasterxml.jackson.databind.ObjectMapper
import jakarta.persistence.*
import org.springframework.data.repository.CrudRepository
import org.springframework.stereotype.Repository
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RestController
#Entity
#Table(name = "a_test_entity")
class AdminTestEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
var id: Int? = null
var name: String? = null
#Column
#Convert(converter = StrListConverter::class)
var interactions: List<Interaction> = emptyList()
}
enum class Interaction { HI, BYE }
class StrListConverter : AttributeConverter<List<Interaction>, String?> {
override fun convertToDatabaseColumn(p0: List<Interaction>): String? = ObjectMapper().writeValueAsString(p0)
override fun convertToEntityAttribute(p0: String?): List<Interaction> =
p0?.let { listOf(*ObjectMapper().readValue(it, Array<Interaction>::class.java)) } ?: emptyList()
}
#Repository
interface AdminTestEntityRepository : CrudRepository<AdminTestEntity, Int?>
#RestController
#RequestMapping("/api/v1/admin/test")
class AdminTestController(private val adminTestEntityRepository: AdminTestEntityRepository) {
#GetMapping("all")
fun getAllTest() = adminTestEntityRepository.findAll()
}
The kicker for this whole issue is that it only seems to be List<Enum> that causes this issue. For example, the following three re-definitions do not cause an instance of this issue:
var interactions: ArrayList<Interaction> = emptyList()
var interactions: List<String> = emptyList()
var interactions: List<DataClass> = emptyList()
What could be the cause of this? Why is it only List<Enum>?

Answer 1

It seems that https://hibernate.atlassian.net/browse/HHH-15624 fixed this issue.