HHH-16081 - Converted collection-as-basic values are considered immutable

HHH-16132 - Dirty checking broken for collection-as-basic mappings (test)

hibernate-core/src/main/java/org/hibernate/boot/model/process/internal/NamedConverterResolution.java

@@ -6,18 +6,21 @@
  */
 package org.hibernate.boot.model.process.internal;
 
+import java.util.Map;
 import java.util.function.Function;
 
+import org.hibernate.annotations.Immutable;
 import org.hibernate.boot.model.convert.internal.ClassBasedConverterDescriptor;
 import org.hibernate.boot.model.convert.spi.ConverterDescriptor;
 import org.hibernate.boot.model.convert.spi.JpaAttributeConverterCreationContext;
 import org.hibernate.boot.registry.classloading.spi.ClassLoaderService;
 import org.hibernate.boot.spi.MetadataBuildingContext;
 import org.hibernate.mapping.BasicValue;
+import org.hibernate.mapping.Collection;
 import org.hibernate.metamodel.mapping.JdbcMapping;
-import org.hibernate.type.descriptor.converter.spi.JpaAttributeConverter;
 import org.hibernate.type.BasicType;
 import org.hibernate.type.descriptor.converter.internal.AttributeConverterMutabilityPlanImpl;
+import org.hibernate.type.descriptor.converter.spi.JpaAttributeConverter;
 import org.hibernate.type.descriptor.java.BasicJavaType;
 import org.hibernate.type.descriptor.java.ImmutableMutabilityPlan;
 import org.hibernate.type.descriptor.java.JavaType;
@@ -112,23 +115,14 @@ public class NamedConverterResolution<J> implements BasicValue.Resolution<J> {
 				? explicitJdbcType
 				: relationalJtd.getRecommendedJdbcType( sqlTypeIndicators );
 
-		final MutabilityPlan<T> explicitMutabilityPlan = explicitMutabilityPlanAccess != null
-				? explicitMutabilityPlanAccess.apply( typeConfiguration )
-				: null;
+		final MutabilityPlan<T> mutabilityPlan = determineMutabilityPlan(
+				explicitMutabilityPlanAccess,
+				typeConfiguration,
+				converter,
+				domainJtd
+		);
 
-
-		final MutabilityPlan<T> mutabilityPlan;
-		if ( explicitMutabilityPlan != null ) {
-			mutabilityPlan = explicitMutabilityPlan;
-		}
-		else if ( ! domainJtd.getMutabilityPlan().isMutable() ) {
-			mutabilityPlan = ImmutableMutabilityPlan.instance();
-		}
-		else {
-			mutabilityPlan = new AttributeConverterMutabilityPlanImpl<>( converter, true );
-		}
-
-		return new NamedConverterResolution<T>(
+		return new NamedConverterResolution<>(
 				domainJtd,
 				relationalJtd,
 				jdbcType,
@@ -138,6 +132,36 @@ public class NamedConverterResolution<J> implements BasicValue.Resolution<J> {
 		);
 	}
 
+	private static <T> MutabilityPlan<T> determineMutabilityPlan(
+			Function<TypeConfiguration, MutabilityPlan> explicitMutabilityPlanAccess,
+			TypeConfiguration typeConfiguration,
+			JpaAttributeConverter<T, ?> converter,
+			JavaType<T> domainJtd) {
+		//noinspection unchecked
+		final MutabilityPlan<T> explicitMutabilityPlan = explicitMutabilityPlanAccess != null
+				? explicitMutabilityPlanAccess.apply( typeConfiguration )
+				: null;
+		if ( explicitMutabilityPlan != null ) {
+			return explicitMutabilityPlan;
+		}
+
+		if ( converter.getConverterJavaType().getJavaTypeClass().isAnnotationPresent( Immutable.class ) ) {
+			return ImmutableMutabilityPlan.instance();
+		}
+
+		if ( !domainJtd.getMutabilityPlan().isMutable()
+				&& !isCollection( domainJtd.getJavaTypeClass() ) ) {
+			return ImmutableMutabilityPlan.instance();
+		}
+
+		return new AttributeConverterMutabilityPlanImpl<>( converter, true );
+	}
+
+	private static boolean isCollection(Class<?> javaType) {
+		return Collection.class.isAssignableFrom( javaType )
+				|| Map.class.isAssignableFrom( javaType );
+	}
+
 
 	private final JavaType<J> domainJtd;
 	private final JavaType<?> relationalJtd;

hibernate-core/src/main/java/org/hibernate/internal/util/collections/CollectionHelper.java

@@ -426,6 +426,16 @@ public final class CollectionHelper {
 		}
 	}
 
+	public static String[] asPairs(Map<String,String> map) {
+		final String[] pairs = new String[ map.size() * 2 ];
+		int i = 0;
+		for ( Map.Entry<String,String> entry : map.entrySet() ) {
+			pairs[i++] = entry.getKey();
+			pairs[i++] = entry.getValue();
+		}
+		return pairs;
+	}
+
 	public static Properties toProperties(Object... pairs) {
 		final Properties properties = new Properties();
 		if ( pairs.length > 0 ) {

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/spi/CollectionJavaType.java

@@ -7,6 +7,7 @@
 package org.hibernate.type.descriptor.java.spi;
 
 import java.lang.reflect.ParameterizedType;
+import java.util.Objects;
 
 import org.hibernate.collection.spi.CollectionSemantics;
 import org.hibernate.collection.spi.PersistentCollection;
@@ -89,17 +90,34 @@ public class CollectionJavaType<C> extends AbstractClassJavaType<C> {
 
 	@Override
 	public boolean areEqual(C one, C another) {
-		return one == another ||
-				(
-						one instanceof PersistentCollection &&
-								( (PersistentCollection<?>) one ).wasInitialized() &&
-								( (PersistentCollection<?>) one ).isWrapper( another )
-				) ||
-				(
-						another instanceof PersistentCollection &&
-								( (PersistentCollection<?>) another ).wasInitialized() &&
-								( (PersistentCollection<?>) another ).isWrapper( one )
-				);
+//		return one == another ||
+//				(
+//						one instanceof PersistentCollection &&
+//								( (PersistentCollection<?>) one ).wasInitialized() &&
+//								( (PersistentCollection<?>) one ).isWrapper( another )
+//				) ||
+//				(
+//						another instanceof PersistentCollection &&
+//								( (PersistentCollection<?>) another ).wasInitialized() &&
+//								( (PersistentCollection<?>) another ).isWrapper( one )
+//				);
+
+
+		if ( one == another ) {
+			return true;
+		}
+
+		if ( one instanceof PersistentCollection ) {
+			final PersistentCollection pc = (PersistentCollection) one;
+			return pc.wasInitialized() && ( pc.isWrapper( another ) || pc.isDirectlyProvidedCollection( another ) );
+		}
+
+		if ( another instanceof PersistentCollection ) {
+			final PersistentCollection pc = (PersistentCollection) another;
+			return pc.wasInitialized() && ( pc.isWrapper( one ) || pc.isDirectlyProvidedCollection( one ) );
+		}
+
+		return Objects.equals( one, another );
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/spi/JavaTypeRegistry.java

@@ -136,7 +136,7 @@ public class JavaTypeRegistry implements JavaTypeBaseline.BaselineTarget, Serial
 				() -> {
 					if ( javaType instanceof ParameterizedType ) {
 						final ParameterizedType parameterizedType = (ParameterizedType) javaType;
-						final JavaType<J> rawType = findDescriptor( ( parameterizedType ).getRawType() );
+						final JavaType<J> rawType = findDescriptor( parameterizedType.getRawType() );
 						if ( rawType != null ) {
 							return rawType.createJavaType( parameterizedType, typeConfiguration );
 						}

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/converted/converter/mutabiity/ConvertedMapImmutableTests.java

@@ -0,0 +1,165 @@
+/*
+ * 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.mapping.converted.converter.mutabiity;
+
+import java.util.Map;
+
+import org.hibernate.annotations.Immutable;
+import org.hibernate.internal.util.collections.CollectionHelper;
+
+import org.hibernate.testing.jdbc.SQLStatementInspector;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.FailureExpected;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Convert;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Steve Ebersole
+ */
+@DomainModel( annotatedClasses = ConvertedMapImmutableTests.TestEntity.class )
+@SessionFactory( useCollectingStatementInspector = true )
+public class ConvertedMapImmutableTests {
+
+	@Test
+	@JiraKey( "HHH-16081" )
+	void testManagedUpdate(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		scope.inTransaction( (session) -> {
+			final TestEntity loaded = session.get( TestEntity.class, 1 );
+			loaded.values.put( "ghi", "789" );
+			statementInspector.clear();
+		} );
+
+		final TestEntity after = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( after.values ).hasSize( 2 );
+	}
+
+	@Test
+	@JiraKey( "HHH-16081" )
+	@FailureExpected( reason = "Fails due to HHH-16132 - Hibernate believes the attribute is dirty, even though it is immutable." )
+	void testMerge(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		final TestEntity loaded = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( loaded.values ).hasSize( 2 );
+
+		loaded.values.put( "ghi", "789" );
+		statementInspector.clear();
+		scope.inTransaction( (session) -> session.merge( loaded ) );
+
+		final TestEntity merged = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( merged.values ).hasSize( 2 );
+	}
+
+	@Test
+	@JiraKey( "HHH-16132" )
+	@FailureExpected( reason = "Fails due to HHH-16132 - Hibernate believes the attribute is dirty, even though it is immutable." )
+	void testDirtyChecking(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		// make changes to a managed entity - should not trigger update since it is immutable
+		scope.inTransaction( (session) -> {
+			final TestEntity managed = session.get( TestEntity.class, 1 );
+			statementInspector.clear();
+			assertThat( managed.values ).hasSize( 2 );
+			// make the change
+			managed.values.put( "ghi", "789" );
+		} );
+		assertThat( statementInspector.getSqlQueries() ).isEmpty();
+
+		// make no changes to a detached entity and merge it - should not trigger update
+		final TestEntity loaded = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( loaded.values ).hasSize( 2 );
+		// make the change
+		loaded.values.put( "ghi", "789" );
+		statementInspector.clear();
+		scope.inTransaction( (session) -> session.merge( loaded ) );
+		// the SELECT
+		assertThat( statementInspector.getSqlQueries() ).hasSize( 1 );
+	}
+
+	@Test
+	@JiraKey( "HHH-16132" )
+	void testNotDirtyChecking(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		// make changes to a managed entity - should not trigger update
+		scope.inTransaction( (session) -> {
+			final TestEntity managed = session.get( TestEntity.class, 1 );
+			statementInspector.clear();
+			assertThat( managed.values ).hasSize( 2 );
+		} );
+		assertThat( statementInspector.getSqlQueries() ).isEmpty();
+
+		// make no changes to a detached entity and merge it - should not trigger update
+		final TestEntity loaded = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( loaded.values ).hasSize( 2 );
+		statementInspector.clear();
+		scope.inTransaction( (session) -> session.merge( loaded ) );
+		// the SELECT
+		assertThat( statementInspector.getSqlQueries() ).hasSize( 1 );
+	}
+
+	@BeforeEach
+	void createTestData(SessionFactoryScope scope) {
+		scope.inTransaction( (session) -> {
+			session.persist( new TestEntity(
+					1,
+					CollectionHelper.toMap(
+							"abc", "123",
+							"def", "456"
+					)
+			) );
+		} );
+	}
+
+	@AfterEach
+	void dropTestData(SessionFactoryScope scope) {
+		scope.inTransaction( (session) -> {
+			session.createMutationQuery( "delete TestEntity" ).executeUpdate();
+		} );
+	}
+
+	@Immutable
+	public static class ImmutableMapConverter extends ConvertedMapMutableTests.MapConverter {
+	}
+
+	@Entity( name = "TestEntity" )
+	@Table( name = "entity_immutable_map" )
+	public static class TestEntity {
+	    @Id
+	    private Integer id;
+
+		@Convert( converter = ImmutableMapConverter.class )
+		@Column( name="vals" )
+		private Map<String,String> values;
+
+		private TestEntity() {
+			// for use by Hibernate
+		}
+
+		public TestEntity(
+				Integer id,
+				Map<String,String> values) {
+			this.id = id;
+			this.values = values;
+		}
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/converted/converter/mutabiity/ConvertedMapMutableTests.java

@@ -0,0 +1,179 @@
+/*
+ * 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.mapping.converted.converter.mutabiity;
+
+import java.util.Map;
+
+import org.hibernate.internal.util.StringHelper;
+import org.hibernate.internal.util.collections.CollectionHelper;
+
+import org.hibernate.testing.jdbc.SQLStatementInspector;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.AttributeConverter;
+import jakarta.persistence.Column;
+import jakarta.persistence.Convert;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Steve Ebersole
+ */
+@JiraKey( "HHH-16081" )
+@DomainModel( annotatedClasses = ConvertedMapMutableTests.TestEntity.class )
+@SessionFactory( useCollectingStatementInspector = true )
+public class ConvertedMapMutableTests {
+
+	@Test
+	void testMutableMap(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		scope.inTransaction( (session) -> {
+			final TestEntity loaded = session.get( TestEntity.class, 1 );
+			assertThat( loaded.values ).hasSize( 2 );
+			loaded.values.put( "ghi", "789" );
+			statementInspector.clear();
+		} );
+		assertThat( statementInspector.getSqlQueries() ).isNotEmpty();
+
+		scope.inTransaction( (session) -> {
+			final TestEntity loaded = session.get( TestEntity.class, 1 );
+			assertThat( loaded.values ).hasSize( 3 );
+			statementInspector.clear();
+		} );
+		assertThat( statementInspector.getSqlQueries() ).isEmpty();
+	}
+
+	@Test
+	void testMutableMapWithMerge(SessionFactoryScope scope) {
+		final TestEntity loaded = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( loaded.values ).hasSize( 2 );
+
+		loaded.values.put( "ghi", "789" );
+		scope.inTransaction( (session) -> session.merge( loaded ) );
+
+		final TestEntity changed = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( changed.values ).hasSize( 3 );
+	}
+
+	@Test
+	@JiraKey( "HHH-16132" )
+	void testDirtyChecking(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		// make changes to a managed entity - should trigger update
+		scope.inTransaction( (session) -> {
+			final TestEntity managed = session.get( TestEntity.class, 1 );
+			statementInspector.clear();
+			assertThat( managed.values ).hasSize( 2 );
+			// make the change
+			managed.values.put( "ghi", "789" );
+		} );
+		assertThat( statementInspector.getSqlQueries() ).hasSize( 1 );
+
+		// make changes to a detached entity and merge it - should trigger update
+		final TestEntity loaded = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( loaded.values ).hasSize( 3 );
+		// make the change
+		loaded.values.put( "jkl", "007" );
+		statementInspector.clear();
+		scope.inTransaction( (session) -> session.merge( loaded ) );
+		// the SELECT + UPDATE
+		assertThat( statementInspector.getSqlQueries() ).hasSize( 2 );
+	}
+
+	@Test
+	@JiraKey( "HHH-16132" )
+	void testNotDirtyChecking(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		// make no changes to a managed entity - should not trigger update
+		scope.inTransaction( (session) -> {
+			final TestEntity managed = session.get( TestEntity.class, 1 );
+			statementInspector.clear();
+			assertThat( managed.values ).hasSize( 2 );
+		} );
+		assertThat( statementInspector.getSqlQueries() ).isEmpty();
+
+		// make no changes to a detached entity and merge it - should not trigger update
+		final TestEntity loaded = scope.fromTransaction( (session) -> session.get( TestEntity.class, 1 ) );
+		assertThat( loaded.values ).hasSize( 2 );
+		statementInspector.clear();
+		scope.inTransaction( (session) -> session.merge( loaded ) );
+		// the SELECT
+		assertThat( statementInspector.getSqlQueries() ).hasSize( 1 );
+	}
+
+	@BeforeEach
+	void createTestData(SessionFactoryScope scope) {
+		scope.inTransaction( (session) -> {
+			session.persist( new TestEntity(
+					1,
+					CollectionHelper.toMap(
+							"abc", "123",
+							"def", "456"
+					)
+			) );
+		} );
+	}
+
+	@AfterEach
+	void dropTestData(SessionFactoryScope scope) {
+		scope.inTransaction( (session) -> {
+			session.createMutationQuery( "delete TestEntity" ).executeUpdate();
+		} );
+	}
+
+	public static class MapConverter implements AttributeConverter<Map<String,String>,String> {
+		@Override
+		public String convertToDatabaseColumn(Map<String,String> map) {
+			if ( CollectionHelper.isEmpty( map ) ) {
+				return null;
+			}
+			return StringHelper.join( ", ", CollectionHelper.asPairs( map ) );
+		}
+
+		@Override
+		public Map<String,String> convertToEntityAttribute(String pairs) {
+			if ( StringHelper.isEmpty( pairs ) ) {
+				return null;
+			}
+			return CollectionHelper.toMap( StringHelper.split( ", ", pairs ) );
+		}
+	}
+
+	@Entity( name = "TestEntity" )
+	@Table( name = "entity_mutable_map" )
+	public static class TestEntity {
+	    @Id
+	    private Integer id;
+
+		@Convert( converter = MapConverter.class )
+		@Column( name = "vals" )
+		private Map<String,String> values;
+
+		private TestEntity() {
+			// for use by Hibernate
+		}
+
+		public TestEntity(
+				Integer id,
+				Map<String,String> values) {
+			this.id = id;
+			this.values = values;
+		}
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/converted/converter/mutabiity/ConvertedMutabilityTests.java

@@ -0,0 +1,188 @@
+/*
+ * 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.mapping.converted.converter.mutabiity;
+
+import java.time.Instant;
+import java.time.format.DateTimeFormatter;
+import java.util.Date;
+
+import org.hibernate.annotations.Immutable;
+import org.hibernate.internal.util.StringHelper;
+
+import org.hibernate.testing.jdbc.SQLStatementInspector;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.AttributeConverter;
+import jakarta.persistence.Convert;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Steve Ebersole
+ */
+@JiraKey( "HHH-16081" )
+@DomainModel( annotatedClasses = ConvertedMutabilityTests.TestEntityWithDates.class )
+@SessionFactory( useCollectingStatementInspector = true )
+public class ConvertedMutabilityTests {
+	private static final Instant START = Instant.now();
+
+	@Test
+	void testImmutableDate(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		scope.inTransaction( (session) -> {
+			final TestEntityWithDates loaded = session.get( TestEntityWithDates.class, 1 );
+
+			statementInspector.clear();
+
+			// change `d2` - because it is immutable, this should not trigger an update
+			loaded.d2.setTime( Instant.EPOCH.toEpochMilli() );
+		} );
+
+		assertThat( statementInspector.getSqlQueries() ).isEmpty();
+
+		scope.inTransaction( (session) -> {
+			final TestEntityWithDates loaded = session.get( TestEntityWithDates.class, 1 );
+			assertThat( loaded.d1.getTime() ).isEqualTo( START.toEpochMilli() );
+		} );
+	}
+
+	@Test
+	void testMutableDate(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+
+		scope.inTransaction( (session) -> {
+			final TestEntityWithDates loaded = session.get( TestEntityWithDates.class, 1 );
+
+			statementInspector.clear();
+
+			// change `d1` - because it is mutable, this should trigger an update
+			loaded.d1.setTime( Instant.EPOCH.toEpochMilli() );
+		} );
+
+		assertThat( statementInspector.getSqlQueries() ).isNotEmpty();
+
+		scope.inTransaction( (session) -> {
+			final TestEntityWithDates loaded = session.get( TestEntityWithDates.class, 1 );
+			assertThat( loaded.d1.getTime() ).isEqualTo( Instant.EPOCH.toEpochMilli() );
+		} );
+	}
+
+	@Test
+	void testDatesWithMerge(SessionFactoryScope scope) {
+		final SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
+		final TestEntityWithDates loaded = scope.fromTransaction( (session) -> session.get( TestEntityWithDates.class, 1 ) );
+
+		loaded.d1.setTime( Instant.EPOCH.toEpochMilli() );
+
+		statementInspector.clear();
+		scope.inTransaction( (session) -> session.merge( loaded ) );
+		assertThat( statementInspector.getSqlQueries() ).isNotEmpty();
+
+		final TestEntityWithDates loaded2 = scope.fromTransaction( (session) -> session.get( TestEntityWithDates.class, 1 ) );
+		assertThat( loaded2.d1.getTime() ).isEqualTo( Instant.EPOCH.toEpochMilli() );
+
+		loaded2.d2.setTime( Instant.EPOCH.toEpochMilli() );
+		statementInspector.clear();
+		scope.inTransaction( (session) -> session.merge( loaded ) );
+		assertThat( statementInspector.getSqlQueries() ).isNotEmpty();
+
+		final TestEntityWithDates loaded3 = scope.fromTransaction( (session) -> session.get( TestEntityWithDates.class, 1 ) );
+		assertThat( loaded3.d2.getTime() ).isEqualTo( START.toEpochMilli() );
+	}
+
+	@BeforeEach
+	void createTestData(SessionFactoryScope scope) {
+		scope.inTransaction( (session) -> {
+			session.persist( new TestEntityWithDates(
+					1,
+					Date.from( START ),
+					Date.from( START )
+			) );
+		} );
+	}
+
+	@AfterEach
+	void dropTestData(SessionFactoryScope scope) {
+		scope.inTransaction( (session) -> {
+			session.createMutationQuery( "delete TestEntityWithDates" ).executeUpdate();
+		} );
+	}
+
+	public static class DateConverter implements AttributeConverter<Date,String> {
+		@Override
+		public String convertToDatabaseColumn(Date date) {
+			if ( date == null ) {
+				return null;
+			}
+			return DateTimeFormatter.ISO_INSTANT.format( date.toInstant() );
+		}
+
+		@Override
+		public Date convertToEntityAttribute(String date) {
+			if ( StringHelper.isEmpty( date ) ) {
+				return null;
+			}
+			return Date.from( Instant.from( DateTimeFormatter.ISO_INSTANT.parse( date ) ) );
+		}
+	}
+
+	@Immutable
+	public static class ImmutableDateConverter implements AttributeConverter<Date,String> {
+		@Override
+		public String convertToDatabaseColumn(Date date) {
+			if ( date == null ) {
+				return null;
+			}
+			return DateTimeFormatter.ISO_INSTANT.format( date.toInstant() );
+		}
+
+		@Override
+		public Date convertToEntityAttribute(String date) {
+			if ( StringHelper.isEmpty( date ) ) {
+				return null;
+			}
+			return Date.from( Instant.from( DateTimeFormatter.ISO_INSTANT.parse( date ) ) );
+		}
+	}
+
+
+	@Entity( name = "TestEntityWithDates" )
+	@Table( name = "entity_dates" )
+	public static class TestEntityWithDates {
+	    @Id
+	    private Integer id;
+
+		@Convert( converter = DateConverter.class )
+		private Date d1;
+		@Convert( converter = ImmutableDateConverter.class )
+		private Date d2;
+
+		private TestEntityWithDates() {
+			// for use by Hibernate
+		}
+
+		public TestEntityWithDates(
+				Integer id,
+				Date d1,
+				Date d2) {
+			this.id = id;
+			this.d1 = d1;
+			this.d2 = d2;
+		}
+	}
+
+}