if the id property is assigned by value,the exception list as below

jakarta.persistence.PersistenceException: Converting org.hibernate.PersistentObjectException to JPA PersistenceException : detached entity passed to persist: demo.jpa.demo2022112104.ProductUUID

if not assigned,the error message is：ids for this class must be manually assigned before calling save()

the domain model is as follows

@Entity
public class ProductUUID {
  @Id
  @GeneratedValue(generator="assigned")
  @GenericGenerator(name="assigned",
		strategy="assigned",
		parameters= {
				@Parameter(name="entity_name",
							value="ProductUUID"
						)
		}
  )
  private String id;
  ...
}