I have a migration issue from hibernate 5.4.32 to hibernate 6: the properties of one of my entities are not properly set. Please find below a simplified model that reproduces this issue.

So, I have Elements and Tags, as presented in the attached diagram:

• Elements have Tags in a relationship ManyToOne, fetch EAGER
• Tags have composite identifiers
• Tag may have a OneToOne relationship “linkedTag”

My sample project is using Lombok / Spring Data :

• Element:

  @Entity
  @Getter
  @Setter
  public class Element {
  
      @EmbeddedId
      private PkComposite id;
  
      @Column(name = "NAME")
      private String name;
  
      @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
      @JoinColumn(name = "ID_TAG")
      private Tag tag;
  
  }

• Tag:

  @Entity
  @Getter
  @Setter
  public class Tag {
  
      @EmbeddedId
      private PkComposite id;
  
      private String name;
  
      @OneToMany(mappedBy = "tag", fetch = FetchType.EAGER)
      private List<Element> elements;
  
      @OneToOne(cascade = CascadeType.ALL)
      @JoinColumn(name = "ID_TAG_LINKED")
      private Tag linkedTag;
  }

• The composite key:

  @Getter
  @Setter
  public class PkComposite implements Serializable {
  
      @Column(name = "ID")
      private Long id;
  
      public PkComposite withId(Long id) {
          this.id = id;
          return this;
      }
  }

• The test class:

  	@Test
  	@Transactional
  	public void issue3_name_not_filled() {
  		// create some data
  		Session session = entityManager.unwrap(Session.class);
  		session.createNativeQuery("insert into TAG (id, NAME) values (100, 'NAME for TAG 100')").executeUpdate();
  		session.createNativeQuery("insert into ELEMENT (id, NAME, ID_TAG) values (200, 'NAME for ELEMENT 200', 100)").executeUpdate();
  
  		// move line to other item
  		Element element200 = elementRepository.findById(new PkComposite().withId(200L)).orElse(null);
  		Assertions.assertNotNull(element200);
  		Assertions.assertNotNull(element200.getTag());
  		Assertions.assertNotNull(element200.getTag().getName(), "Tag name is null !");
  	}

The test fails since the name property is not set on Element’s Tag. None of tag’s properties is set, except for its identifier.

Few remarks:

• the issue is reproduced whether the Element identifier is composite or simple (may be Long as example)
• The OneToMany relationship to Element in Tag class may also be lazy - in my project it is actually LAZY with LazyCollection(LazyCollectionOption.FALSE)
• If I remove the “linkedTag” the issue in no longer reproduced

But if I set the “linkedTag“:

	@Test
	@Transactional
	public void issue3_tag_not_properly_set() {
		// create some data
		Session session = entityManager.unwrap(Session.class);
		session.createNativeQuery("insert into TAG (id, NAME) values (101, 'NAME for LINKED TAG 101')").executeUpdate();
		session.createNativeQuery("insert into TAG (id, NAME, ID_TAG_LINKED) values (100, 'NAME for TAG 100', 101)").executeUpdate();
		session.createNativeQuery("insert into ELEMENT (id, NAME, ID_TAG) values (200, 'NAME for ELEMENT 200', 100)").executeUpdate();

			// move line to other item
		Element element200 = elementRepository.findById(new PkComposite().withId(200L)).orElse(null);
		Assertions.assertNotNull(element200);
		Assertions.assertNotNull(element200.getTag());
		Assertions.assertNotNull(element200.getTag().getId());
		Assertions.assertEquals(100L, element200.getTag().getId().getId(), "Tag is not the good one !");
		Assertions.assertEquals("NAME for TAG 100", element200.getTag().getName(), "Tag properties are not good !");
	}

The Element’s Tag’s properties are set, but with wrong values, those of the linked Tag.

I have attached the tests logs and if needed, I can also share my sample project.