Cannot inject repository into custom repository via constructor but with @Autowired

[Ch4s3r]

The code below was working before updating to Spring version 2.4.3 on version 2.3.5.RELEASE.
It's not possible anymore to inject a repository via constructor into a custom repository, otherwise you get a circular dependency error.
Which you do not get if you use field injection with @Autowired.

Is this maybe a regression or did something get changed that this is not possible anymore in the new version?

@Entity
class User {
    @Id
    val id: Long = 0L
}

@Repository
interface UserRepository : JpaRepository<User, Long>, CustomUserRepository

interface CustomUserRepository {
    fun saveCustom(user: User): User?
}

class CustomUserRepositoryImpl(
    val userRepository: UserRepository
) : CustomUserRepository {

//    @Autowired
//    lateinit var userRepository: UserRepository

    override fun saveCustom(user: User)= userRepository.save(user)
}

┌─────┐
|  customUserRepositoryImpl defined in file [.../custom_repository/build/classes/kotlin/main/com/example/demo/CustomUserRepositoryImpl.class]
↑     ↓
|  userRepository defined in com.example.demo.UserRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration
↑     ↓
|  (inner bean)#31691525
↑     ↓
|  customUserRepositoryImplFragment
└─────┘

[Ch4s3r]

Found a workaround by adding @Lazy to the constructor worked, but this seems more of like a workaround.

class CustomUserRepositoryImpl(
    @Lazy val userRepository: UserRepository
) : CustomUserRepository {

[Ch4s3r]

Just pinpointed the version.
With spring boot 2.4.0 it works and since 2.4.1 it's throwing a circular dependency error.

[mp911de]

I think what you're experiencing here is a change in Spring Boot how JPA repositories are bootstrapped. Generally speaking, fragments are required at the time of constructing the actual repository. Therefore, you cannot inject a direct instance of the repository to be created into a fragment or a custom repository implementation. You can use @Lazy (proxying the bean) or a lookup via ApplicationContext or ObjectProvider.