HHH-16337 Bytecode enhancement : ElementCollection is not deleted when replaced

hibernate-core/src/main/java/org/hibernate/event/internal/WrapVisitor.java

@@ -12,6 +12,7 @@ import org.hibernate.bytecode.enhance.spi.interceptor.EnhancementAsProxyLaziness
 import org.hibernate.bytecode.enhance.spi.interceptor.LazyAttributeLoadingInterceptor;
 import org.hibernate.collection.spi.PersistentCollection;
 import org.hibernate.engine.spi.CollectionEntry;
+import org.hibernate.engine.spi.CollectionKey;
 import org.hibernate.engine.spi.EntityEntry;
 import org.hibernate.engine.spi.PersistenceContext;
 import org.hibernate.engine.spi.PersistentAttributeInterceptor;
@@ -114,8 +115,6 @@ public class WrapVisitor extends ProxyVisitor {
 							&& ((LazyAttributeLoadingInterceptor)attributeInterceptor).isAttributeLoaded( persister.getAttributeMapping().getAttributeName() ) ) {
 						final EntityEntry entry = persistenceContext.getEntry( entity );
 						if ( entry.isExistsInDatabase() ) {
-							// the collection has not been initialized and new collection values have been assigned,
-							// we need to be sure to delete all the collection elements before inserting the new ones
 							final AbstractEntityPersister entityDescriptor =
 									(AbstractEntityPersister) persister.getOwnerEntityPersister();
 							final Object key = entityDescriptor.getCollectionKey(
@@ -124,14 +123,23 @@ public class WrapVisitor extends ProxyVisitor {
 									entry,
 									session
 							);
-							final PersistentCollection<?> collectionInstance = persister.getCollectionSemantics()
-									.instantiateWrapper( key, persister, session );
-							collectionInstance.setOwner( entity );
-							persistenceContext.addUninitializedCollection( persister, collectionInstance, key );
+							PersistentCollection<?> collectionInstance = persistenceContext.getCollection(
+									new CollectionKey( persister, key )
+							);
 
-							final CollectionEntry collectionEntry = persistenceContext
-									.getCollectionEntry( collectionInstance );
-							collectionEntry.setDoremove( true );
+							if ( collectionInstance == null ) {
+								// the collection has not been initialized and new collection values have been assigned,
+								// we need to be sure to delete all the collection elements before inserting the new ones
+								collectionInstance = persister.getCollectionSemantics().instantiateWrapper(
+										key,
+										persister,
+										session
+								);
+								persistenceContext.addUninitializedCollection( persister, collectionInstance, key );
+								final CollectionEntry collectionEntry = persistenceContext.getCollectionEntry(
+										collectionInstance );
+								collectionEntry.setDoremove( true );
+							}
 						}
 					}
 				}

hibernate-core/src/test/java/org/hibernate/orm/test/bytecode/enhancement/collectionelement/flush/ElementCollectionFlushAfterQueryTest.java

@@ -0,0 +1,128 @@
+package org.hibernate.orm.test.bytecode.enhancement.collectionelement.flush;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.bytecode.enhancement.BytecodeEnhancerRunner;
+import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import jakarta.persistence.CollectionTable;
+import jakarta.persistence.Column;
+import jakarta.persistence.ElementCollection;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+@RunWith(BytecodeEnhancerRunner.class)
+@TestForIssue(jiraKey = "HHH-16337")
+public class ElementCollectionFlushAfterQueryTest extends BaseCoreFunctionalTestCase {
+	private static final Long MY_ENTITY_ID = 1l;
+
+	@Override
+	protected Class[] getAnnotatedClasses() {
+		return new Class[] {
+				MyEntity.class,
+				MyOtherEntity.class
+		};
+	}
+
+	@Test
+	public void testAutoFlush() {
+		inTransaction(
+				session -> {
+					MyEntity myEntity = new MyEntity( MY_ENTITY_ID, "my entity" );
+					myEntity.addRedirectUris( "1" );
+					session.persist( myEntity );
+				}
+		);
+
+		inTransaction(
+				session -> {
+					MyEntity myEntity = session.find( MyEntity.class, MY_ENTITY_ID );
+
+					Set<String> set = new HashSet<>();
+					set.add( "3" );
+					myEntity.setRedirectUris( set );
+
+					session.createQuery( "from MyOtherEntity ", MyOtherEntity.class ).getResultList();
+				}
+		);
+
+		inTransaction(
+				session -> {
+					MyEntity myEntity = session.find( MyEntity.class, MY_ENTITY_ID );
+					Set<String> redirectUris = myEntity.getRedirectUris();
+					assertThat( redirectUris.size() ).isEqualTo( 1 );
+					assertThat( redirectUris.contains( "3" ) );
+				}
+		);
+
+	}
+
+	@Entity(name = "MyEntity")
+	public static class MyEntity {
+		@Id
+		private Long id;
+
+		private String name;
+
+		@ElementCollection
+		@Column(name = "val")
+		@CollectionTable(name = "REDIRECT_URIS", joinColumns = { @JoinColumn(name = "ID") })
+		protected Set<String> redirectUris = new HashSet<>();
+
+		public MyEntity() {
+		}
+
+		public MyEntity(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public Long getId() {
+			return this.id;
+		}
+
+		public Set<String> getRedirectUris() {
+			return redirectUris;
+		}
+
+		public void setRedirectUris(Set<String> redirectUris) {
+			this.redirectUris = redirectUris;
+		}
+
+		public void addRedirectUris(String redirectUri) {
+			this.redirectUris.add( redirectUri );
+		}
+	}
+
+	@Entity(name = "MyOtherEntity")
+	public class MyOtherEntity {
+
+		@Id
+		private Long id;
+
+		private String name;
+
+		public MyOtherEntity() {
+		}
+
+		public MyOtherEntity(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public Long getId() {
+			return this.id;
+		}
+
+		public void setId(Long id) {
+			this.id = id;
+		}
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/bytecode/enhancement/collectionelement/recreate/BytecodeEnhancementElementCollectionRecreateCollectionsInDefaultGroupTest.java

@@ -0,0 +1,224 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.orm.test.bytecode.enhancement.collectionelement.recreate;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.hibernate.boot.SessionFactoryBuilder;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.bytecode.enhancement.BytecodeEnhancerRunner;
+import org.hibernate.testing.bytecode.enhancement.EnhancementOptions;
+import org.hibernate.testing.junit4.BaseNonConfigCoreFunctionalTestCase;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import jakarta.persistence.ElementCollection;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.OrderColumn;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertTrue;
+
+@RunWith(BytecodeEnhancerRunner.class)
+@EnhancementOptions(lazyLoading = true)
+@TestForIssue(jiraKey = "HHH-14387")
+public class BytecodeEnhancementElementCollectionRecreateCollectionsInDefaultGroupTest
+		extends BaseNonConfigCoreFunctionalTestCase {
+
+	@Override
+	protected Class[] getAnnotatedClasses() {
+		return new Class[] {
+				MyEntity.class
+		};
+	}
+
+	@Override
+	protected void configureSessionFactoryBuilder(SessionFactoryBuilder sfb) {
+		super.configureSessionFactoryBuilder( sfb );
+		sfb.applyCollectionsInDefaultFetchGroup( true );
+	}
+
+	@Before
+	public void check() {
+		inSession(
+				session ->
+						assertTrue( session.getSessionFactory().getSessionFactoryOptions()
+											.isCollectionsInDefaultFetchGroupEnabled() )
+		);
+	}
+
+
+	@After
+	public void tearDown() {
+		inTransaction(
+				session ->
+						session.createQuery( "delete from myentity" ).executeUpdate()
+		);
+	}
+
+	@Test
+	public void testRecreateCollection() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			entity.setElements( Arrays.asList( "two", "three" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.containsExactlyInAnyOrder( "two", "three" );
+		} );
+	}
+
+	@Test
+	public void testRecreateCollectionFind() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			entity.setElements( Arrays.asList( "two", "three" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.containsExactlyInAnyOrder( "two", "three" );
+		} );
+	}
+
+	@Test
+	public void testDeleteCollection() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			entity.setElements( new ArrayList<>() );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.isEmpty();
+		} );
+	}
+
+	@Test
+	public void testDeleteCollectionFind() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			entity.setElements( new ArrayList<>() );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.isEmpty();
+		} );
+	}
+
+	@Test
+	public void testLoadAndCommitTransactionDoesNotDeleteCollection() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session ->
+							   session.get( MyEntity.class, 1 )
+		);
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.containsExactlyInAnyOrder( "one", "two", "four" );
+		} );
+
+	}
+
+	@Test
+	public void testLoadAndCommitTransactionDoesNotDeleteCollectionFind() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session ->
+							   session.find( MyEntity.class, 1 )
+		);
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.containsExactlyInAnyOrder( "one", "two", "four" );
+		} );
+
+	}
+
+	@Entity(name = "myentity")
+	public static class MyEntity {
+		@Id
+		private Integer id;
+
+		@ElementCollection
+		@OrderColumn
+		private List<String> elements;
+
+		public Integer getId() {
+			return id;
+		}
+
+		public void setId(Integer id) {
+			this.id = id;
+		}
+
+		public List<String> getElements() {
+			return elements;
+		}
+
+		public void setElements(List<String> elements) {
+			this.elements = elements;
+		}
+
+	}
+
+}

hibernate-core/src/test/java/org/hibernate/orm/test/bytecode/enhancement/collectionelement/recreate/BytecodeEnhancementElementCollectionRecreateTest.java

@@ -0,0 +1,222 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.orm.test.bytecode.enhancement.collectionelement.recreate;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.hibernate.boot.SessionFactoryBuilder;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.bytecode.enhancement.BytecodeEnhancerRunner;
+import org.hibernate.testing.bytecode.enhancement.EnhancementOptions;
+import org.hibernate.testing.junit4.BaseNonConfigCoreFunctionalTestCase;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import jakarta.persistence.ElementCollection;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.OrderColumn;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertFalse;
+
+@RunWith(BytecodeEnhancerRunner.class)
+@EnhancementOptions(lazyLoading = true)
+@TestForIssue(jiraKey = "HHH-14387")
+public class BytecodeEnhancementElementCollectionRecreateTest extends BaseNonConfigCoreFunctionalTestCase {
+
+	@Override
+	protected Class[] getAnnotatedClasses() {
+		return new Class[] {
+				MyEntity.class
+		};
+	}
+
+	@Override
+	protected void configureSessionFactoryBuilder(SessionFactoryBuilder sfb) {
+		super.configureSessionFactoryBuilder( sfb );
+		sfb.applyCollectionsInDefaultFetchGroup( false );
+	}
+
+	@Before
+	public void check() {
+		inSession(
+				session ->
+						assertFalse( session.getSessionFactory().getSessionFactoryOptions()
+											 .isCollectionsInDefaultFetchGroupEnabled() )
+		);
+	}
+
+	@After
+	public void tearDown() {
+		inTransaction(
+				session ->
+						session.createQuery( "delete from myentity" ).executeUpdate()
+		);
+	}
+
+	@Test
+	public void testRecreateCollection() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			entity.setElements( Arrays.asList( "two", "three" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.containsExactlyInAnyOrder( "two", "three" );
+		} );
+	}
+
+	@Test
+	public void testRecreateCollectionFind() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			entity.setElements( Arrays.asList( "two", "three" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.containsExactlyInAnyOrder( "two", "three" );
+		} );
+	}
+
+	@Test
+	public void testDeleteCollection() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			entity.setElements( new ArrayList<>() );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.isEmpty();
+		} );
+	}
+
+	@Test
+	public void testDeleteCollectionFind() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			entity.setElements( new ArrayList<>() );
+		} );
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.isEmpty();
+		} );
+	}
+
+	@Test
+	public void testLoadAndCommitTransactionDoesNotDeleteCollection() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session ->
+							   session.get( MyEntity.class, 1 )
+		);
+
+		inTransaction( session -> {
+			MyEntity entity = session.get( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.containsExactlyInAnyOrder( "one", "two", "four" );
+		} );
+
+	}
+
+	@Test
+	public void testLoadAndCommitTransactionDoesNotDeleteCollectionFind() {
+		inTransaction( session -> {
+			MyEntity entity = new MyEntity();
+			entity.setId( 1 );
+			entity.setElements( Arrays.asList( "one", "two", "four" ) );
+			session.persist( entity );
+		} );
+
+		inTransaction( session ->
+							   session.find( MyEntity.class, 1 )
+		);
+
+		inTransaction( session -> {
+			MyEntity entity = session.find( MyEntity.class, 1 );
+			assertThat( entity.getElements() )
+					.containsExactlyInAnyOrder( "one", "two", "four" );
+		} );
+
+	}
+
+	@Entity(name = "myentity")
+	public static class MyEntity {
+		@Id
+		private Integer id;
+
+		@ElementCollection
+		@OrderColumn
+		private List<String> elements;
+
+		public Integer getId() {
+			return id;
+		}
+
+		public void setId(Integer id) {
+			this.id = id;
+		}
+
+		public List<String> getElements() {
+			return elements;
+		}
+
+		public void setElements(List<String> elements) {
+			this.elements = elements;
+		}
+
+	}
+
+}

hibernate-core/src/test/java/org/hibernate/orm/test/bytecode/enhancement/flush/CollectionFlushAfterQueryTest.java

@@ -0,0 +1,157 @@
+package org.hibernate.orm.test.bytecode.enhancement.flush;
+
+import java.util.HashSet;
+import java.util.Optional;
+import java.util.Set;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.bytecode.enhancement.BytecodeEnhancerRunner;
+import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.OneToMany;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+@RunWith(BytecodeEnhancerRunner.class)
+@TestForIssue(jiraKey = "HHH-16337")
+public class CollectionFlushAfterQueryTest extends BaseCoreFunctionalTestCase {
+
+	private static final Long MY_ENTITY_ID = 1l;
+
+	@Override
+	protected Class[] getAnnotatedClasses() {
+		return new Class[] {
+				CollectionFlushAfterQueryTest.MyEntity.class,
+				CollectionFlushAfterQueryTest.MyOtherEntity.class,
+				CollectionFlushAfterQueryTest.MyAnotherEntity.class
+		};
+	}
+
+	@Test
+	public void testAutoFlush() {
+		inTransaction(
+				session -> {
+					MyEntity myEntity = new MyEntity( MY_ENTITY_ID, "my entity" );
+					MyOtherEntity otherEntity = new MyOtherEntity( 2l, "my other entity" );
+					myEntity.addOtherEntity( otherEntity );
+					session.persist( otherEntity );
+					session.persist( myEntity );
+				}
+		);
+
+		inTransaction(
+				session -> {
+					MyEntity myEntity = session.find( MyEntity.class, MY_ENTITY_ID );
+
+					MyOtherEntity otherEntity = new MyOtherEntity( 3l, "my new other entity" );
+					Set<MyOtherEntity> set = new HashSet<>();
+					set.add( otherEntity );
+					myEntity.setOtherEntities( set );
+
+					session.createQuery( "from MyAnotherEntity ", MyAnotherEntity.class ).getResultList();
+				}
+		);
+
+		inTransaction(
+				session -> {
+					MyEntity myEntity = session.find( MyEntity.class, MY_ENTITY_ID );
+					Set<MyOtherEntity> redirectUris = myEntity.getOtherEntities();
+					assertThat( redirectUris.size() ).isEqualTo( 1 );
+
+					Optional<MyOtherEntity> first = redirectUris.stream().findFirst();
+					assertThat( first.get().getName() ).isEqualTo( "my new other entity" );
+				}
+		);
+
+	}
+
+	@Entity(name = "MyEntity")
+	public static class MyEntity {
+		@Id
+		private Long id;
+
+		private String name;
+
+		@OneToMany(cascade = CascadeType.ALL)
+		protected Set<MyOtherEntity> otherEntities = new HashSet<>();
+
+		public MyEntity() {
+		}
+
+		public MyEntity(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public Long getId() {
+			return this.id;
+		}
+
+		public Set<MyOtherEntity> getOtherEntities() {
+			return otherEntities;
+		}
+
+		public void setOtherEntities(Set<MyOtherEntity> otherEntities) {
+			this.otherEntities = otherEntities;
+		}
+
+		public void addOtherEntity(MyOtherEntity otherEntity) {
+			this.otherEntities.add( otherEntity );
+		}
+	}
+
+	@Entity(name = "MyOtherEntity")
+	public static class MyOtherEntity {
+
+		@Id
+		private Long id;
+
+		private String name;
+
+		public MyOtherEntity() {
+		}
+
+		public MyOtherEntity(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public Long getId() {
+			return this.id;
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
+
+	@Entity(name = "MyAnotherEntity")
+	public static class MyAnotherEntity {
+
+		@Id
+		private Long id;
+
+		private String name;
+
+		public MyAnotherEntity() {
+		}
+
+		public MyAnotherEntity(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public Long getId() {
+			return this.id;
+		}
+
+		public void setId(Long id) {
+			this.id = id;
+		}
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/bytecode/enhancement/merge/MergeUnsavedEntitiesTest.java

@@ -6,8 +6,8 @@ import java.util.List;
 import org.hibernate.testing.TestForIssue;
 import org.hibernate.testing.bytecode.enhancement.BytecodeEnhancerRunner;
 import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
+import org.junit.After;
 import org.junit.Test;
-import org.junit.jupiter.api.AfterEach;
 import org.junit.runner.RunWith;
 
 import jakarta.persistence.Entity;
@@ -21,9 +21,11 @@ import static jakarta.persistence.CascadeType.MERGE;
 import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
 
 @RunWith(BytecodeEnhancerRunner.class)
-@TestForIssue( jiraKey = "HHH-16322")
+@TestForIssue(jiraKey = "HHH-16322")
 public class MergeUnsavedEntitiesTest extends BaseCoreFunctionalTestCase {
 
+	public static final String CHILD_NAME = "first child";
+
 	@Override
 	protected Class<?>[] getAnnotatedClasses() {
 		return new Class[] {
@@ -32,23 +34,13 @@ public class MergeUnsavedEntitiesTest extends BaseCoreFunctionalTestCase {
 		};
 	}
 
-	@AfterEach
-	public void tearDown() {
-		inTransaction(
-				session -> {
-					session.createMutationQuery( "delete from Child" ).executeUpdate();
-					session.createMutationQuery( "delete from Parent" ).executeUpdate();
-				}
-		);
-	}
-
 	@Test
 	public void testMerge() {
 		inTransaction(
 				session -> {
 					Parent parent = new Parent( 1l, 2l );
 					parent = session.merge( parent );
-					Child child = new Child( 2l, "first child" );
+					Child child = new Child( 2l, CHILD_NAME );
 					child = session.merge( child );
 					parent.addChild( child );
 					parent.getId();
@@ -59,6 +51,8 @@ public class MergeUnsavedEntitiesTest extends BaseCoreFunctionalTestCase {
 				session -> {
 					Parent parent = session.find( Parent.class, 1l );
 					assertThat( parent.getChildren().size() ).isEqualTo( 1 );
+					Child child = parent.getChildren().get( 0 );
+					assertThat( child.getName() ).isEqualTo( CHILD_NAME );
 				}
 		);
 
@@ -72,20 +66,16 @@ public class MergeUnsavedEntitiesTest extends BaseCoreFunctionalTestCase {
 		inTransaction(
 				session -> {
 					Parent parent = session.find( Parent.class, 1l );
-					parent.setChildren( new ArrayList<>() );
-					session.merge( parent );
-				}
-		);
+					assertThat( parent.getChildren().size() ).isEqualTo( 1 );
+					Child child = parent.getChildren().get( 0 );
+
+					assertThat( child.getName() ).isEqualTo( CHILD_NAME );
 
-		inTransaction(
-				session -> {
-					Parent parent = session.find( Parent.class, 1l );
-					assertThat( parent.getChildren().size() ).isEqualTo( 0 );
 				}
 		);
 	}
 
-	@Entity(name = "parent")
+	@Entity(name = "Parent")
 	@Table(name = "parent")
 	public static class Parent {
 		@Id
@@ -139,7 +129,7 @@ public class MergeUnsavedEntitiesTest extends BaseCoreFunctionalTestCase {
 		}
 	}
 
-	@Entity
+	@Entity(name = "Child")
 	@Table(name = "child")
 	public static class Child {
 
@@ -175,6 +165,9 @@ public class MergeUnsavedEntitiesTest extends BaseCoreFunctionalTestCase {
 			this.parent = parent;
 		}
 
+		public String getName() {
+			return name;
+		}
 	}
 
 }