How to insert JSON data to postgres using JPA + Spring boot + Kotlin?

How can i insert JSON data to postgres using JPA without using the named query?

If i send PGObject to insert (using Converter) it gives error-> Coulmn "column_name" is type JSON but getting byte type

@Entity
@Table(name="users")
data class User{
   @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id") val identifier: Int? = null,
   @Convertor(JSONConvertor::class.java)
   @Column(name = "user_detial") var userDetail: UserDetail? = null,
}


@Convertor
class JSONConvertor : AttributeConverter<UserDetail, PGObject> {
  override fun convertToDatabaseColumn(UserDetail attribute) {
   try {
      val userDetail = mapper.writeValueAsString(attribute);
      var pgObject = PGObject()
      pgObject.type = "json"
      pgObject.value = userDeatail
      return pgObject
   } catch (JsonProcessingException e) {
      throw new RuntimeException("Cannot serialize", e);
   }
  }
}

data class UserDetail(
   val name: String,
   val address: String? = null 
)

and calling from service using JPA repository->

val userDetail = UserDetail(name= "abc" address="some address") jpaRepo.save(userDetail)

What i am doing wrong into it?