HHH-15800 introduce EventType + EventTypeSets in place of the previous "two booleans" approach

I hope @sebersole likes this better.

re-deprecate GenerationTime since the way forward is EventType

hibernate-core/src/main/java/org/hibernate/annotations/CurrentTimestamp.java

@@ -10,6 +10,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
 
 import org.hibernate.Remove;
+import org.hibernate.generator.EventType;
 import org.hibernate.generator.internal.CurrentTimestampGeneration;
 import org.hibernate.tuple.GenerationTiming;
 
@@ -17,6 +18,8 @@ import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
 import static java.lang.annotation.ElementType.FIELD;
 import static java.lang.annotation.ElementType.METHOD;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;
+import static org.hibernate.generator.EventType.INSERT;
+import static org.hibernate.generator.EventType.UPDATE;
 
 /**
  * Specifies that the annotated field of property is a generated timestamp,
@@ -68,9 +71,9 @@ public @interface CurrentTimestamp {
 	 * Determines when the timestamp is generated. But default, it is updated
 	 * when any SQL {@code insert} or {@code update} statement is executed.
 	 * If it should be generated just once, on the initial SQL {@code insert},
-	 * explicitly specify {@link GenerationTime#INSERT event = INSERT}.
+	 * explicitly specify {@link EventType#INSERT event = INSERT}.
 	 */
-	GenerationTime event() default GenerationTime.INSERT_OR_UPDATE;
+	EventType[] event() default {INSERT, UPDATE};
 
 	/**
 	 * Determines when the timestamp is generated. But default, it is updated

hibernate-core/src/main/java/org/hibernate/annotations/Generated.java

@@ -11,8 +11,12 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.hibernate.generator.EventType;
 import org.hibernate.generator.internal.GeneratedGeneration;
 
+import static org.hibernate.generator.EventType.INSERT;
+import static org.hibernate.generator.EventType.UPDATE;
+
 /**
  * Specifies that the value of the annotated property is generated by the
  * database. The generated value will be automatically retrieved using a
@@ -59,16 +63,15 @@ public @interface Generated {
 	 * Specifies the events that cause the value to be generated by the
 	 * database.
 	 * <ul>
-	 * <li>If {@link GenerationTime#INSERT}, the generated value will be
+	 * <li>If {@link EventType#INSERT} is included, the generated value
-	 *     selected after each SQL {@code insert} statement is executed.
+	 *     will be selected after each SQL {@code insert} statement is
-	 * <li>If {@link GenerationTime#UPDATE}, the generated value will be
+	 *     executed.
-	 *     selected after each SQL {@code update} statement is executed.
+	 * <li>If {@link EventType#UPDATE} is included, the generated value
-	 * <li>If {@link GenerationTime#INSERT_OR_UPDATE}, the generated value
+	 *     will be selected after each SQL {@code update} statement is
-	 *     will be selected after each SQL {@code insert} or {@code update}
+	 *     executed.
-	 *     statement is executed.
 	 * </ul>
 	 */
-	GenerationTime event() default GenerationTime.INSERT_OR_UPDATE;
+	EventType[] event() default {INSERT, UPDATE};
 
 	/**
 	 * Specifies the events that cause the value to be generated by the

hibernate-core/src/main/java/org/hibernate/annotations/GenerationTime.java

@@ -8,8 +8,12 @@ package org.hibernate.annotations;
 
 import org.hibernate.AssertionFailure;
 import org.hibernate.Internal;
+import org.hibernate.generator.EventType;
+import org.hibernate.generator.EventTypeSets;
 import org.hibernate.tuple.GenerationTiming;
 
+import java.util.EnumSet;
+
 /**
  * Represents a class of events involving interaction with the database
  * that causes generation of a new value. Intended for use with the
@@ -19,7 +23,10 @@ import org.hibernate.tuple.GenerationTiming;
  *
  * @see Generated
  * @see CurrentTimestamp
+ *
+ * @deprecated use {@link EventType} and {@link EventTypeSets} instead
  */
+@Deprecated(since = "6.2")
 public enum GenerationTime {
 	/**
 	 * Indicates that a value is never generated.
@@ -37,30 +44,22 @@ public enum GenerationTime {
 	UPDATE,
 	/**
 	 * Indicates that a new value is generated on insert and on update.
-	 *
-	 * @since 6.2
 	 */
-	INSERT_OR_UPDATE,
-	/**
-	 * Indicates that a new value is generated on insert and on update.
-	 *
-	 * @deprecated use {@link #INSERT_OR_UPDATE}
-	 */
-	@Deprecated(since = "6.2")
 	ALWAYS;
 
-	/**
+	public EnumSet<EventType> eventTypes() {
-	 * @return {@code true} if a new value is generated when an insert is executed
+		switch (this) {
-	 */
+			case NEVER:
-	public boolean includesInsert() {
+				return EventTypeSets.NONE;
-		return getEquivalent().includesInsert();
+			case ALWAYS:
-	}
+				return EventTypeSets.ALL;
-
+			case INSERT:
-	/**
+				return EventTypeSets.INSERT_ONLY;
-	 * @return {@code true} if a new value is generated when an update is executed
+			case UPDATE:
-	 */
+				return EventTypeSets.UPDATE_ONLY;
-	public boolean includesUpdate() {
+			default:
-		return getEquivalent().includesUpdate();
+				throw new AssertionFailure("unknown event");
+		}
 	}
 
 	/**
@@ -70,7 +69,6 @@ public enum GenerationTime {
 	public GenerationTiming getEquivalent() {
 		switch (this) {
 			case ALWAYS:
-			case INSERT_OR_UPDATE:
 				return GenerationTiming.ALWAYS;
 			case INSERT:
 				return GenerationTiming.INSERT;

hibernate-core/src/main/java/org/hibernate/cfg/annotations/PropertyBinder.java

@@ -572,12 +572,12 @@ public class PropertyBinder {
 
 	private static void checkVersionGenerationAlways(XProperty property, Generator generator) {
 		if ( property.isAnnotationPresent(Version.class) ) {
-			if ( !generator.generatedOnInsert() ) {
+			if ( !generator.generatesOnInsert() ) {
 				throw new AnnotationException("Property '" + property.getName()
 						+ "' is annotated '@Version' but has a 'Generator' which does not generate on inserts"
 				);
 			}
-			if ( !generator.generatedOnUpdate() ) {
+			if ( !generator.generatesOnUpdate() ) {
 				throw new AnnotationException("Property '" + property.getName()
 						+ "' is annotated '@Version' but has a 'Generator' which does not generate on updates"
 				);
@@ -586,11 +586,11 @@ public class PropertyBinder {
 	}
 
 	private static void checkIdGeneratorTiming(Class<? extends Annotation> annotationType, Generator generator) {
-		if ( !generator.generatedOnInsert() ) {
+		if ( !generator.generatesOnInsert() ) {
 			throw new MappingException( "Annotation '" + annotationType
 					+ "' is annotated 'IdGeneratorType' but the given 'Generator' does not generate on inserts");
 		}
-		if ( generator.generatedOnUpdate() ) {
+		if ( generator.generatesOnUpdate() ) {
 			throw new MappingException( "Annotation '" + annotationType
 					+ "' is annotated 'IdGeneratorType' but the given 'Generator' generates on updates (it must generate only on inserts)");
 		}

hibernate-core/src/main/java/org/hibernate/engine/internal/Nullability.java

@@ -129,7 +129,7 @@ public final class Nullability {
 	}
 
 	private static boolean generated(Generator generator) {
-		return generator != null && generator.isNotNever();
+		return generator != null && generator.generatesSometimes();
 	}
 
 	/**

hibernate-core/src/main/java/org/hibernate/generator/EventType.java

@@ -0,0 +1,29 @@
+/*
+ * 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.generator;
+
+/**
+ * Enumerates event types that can result in generation of a new value.
+ * A {@link Generator} must specify which events it responds to, by
+ * implementing {@link Generator#getEventTypes()}.
+ * <p>
+ * We usually work with {@linkplain EventTypeSets sets} of event types,
+ * even though there are only two types.
+ *
+ * @author Gavin King
+ *
+ * @since 6.2
+ *
+ * @see Generator
+ * @see org.hibernate.annotations.Generated
+ * @see org.hibernate.annotations.CurrentTimestamp
+ * @see EventTypeSets
+ */
+public enum EventType {
+	INSERT,
+	UPDATE;
+}

hibernate-core/src/main/java/org/hibernate/generator/EventTypeSets.java

@@ -0,0 +1,35 @@
+/*
+ * 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.generator;
+
+import java.util.EnumSet;
+import java.util.Set;
+
+import static org.hibernate.generator.EventType.INSERT;
+import static org.hibernate.generator.EventType.UPDATE;
+
+/**
+ * For convenience, enumerates the possible combinations of {@link EventType}.
+ * <p>
+ * This list supersedes the enumerations {@link org.hibernate.annotations.GenerationTime}
+ * and {@link org.hibernate.tuple.GenerationTiming} from older versions of Hibernate.
+ *
+ * @author Gavin King
+ *
+ * @since 6.2
+ */
+public class EventTypeSets {
+	public static final EnumSet<EventType> NONE = EnumSet.noneOf(EventType.class);
+	public static final EnumSet<EventType> INSERT_ONLY = EnumSet.of(INSERT);
+	public static final EnumSet<EventType> UPDATE_ONLY = EnumSet.of(UPDATE);
+	public static final EnumSet<EventType> INSERT_AND_UPDATE = EnumSet.of(INSERT, UPDATE);
+	public static final EnumSet<EventType> ALL = EnumSet.allOf(EventType.class);
+
+	public static EnumSet<EventType> fromArray(EventType[] types) {
+		return EnumSet.copyOf( Set.of(types) );
+	}
+}

hibernate-core/src/main/java/org/hibernate/generator/Generator.java

@@ -10,6 +10,10 @@ import org.hibernate.engine.spi.SharedSessionContractImplementor;
 import org.hibernate.tuple.ValueGenerator;
 
 import java.io.Serializable;
+import java.util.EnumSet;
+
+import static org.hibernate.generator.EventType.INSERT;
+import static org.hibernate.generator.EventType.UPDATE;
 
 /**
  * Describes the generation of values of a certain field or property of an entity. A generated
@@ -38,6 +42,14 @@ import java.io.Serializable;
  * <li>declare a constructor which accepts just the annotation instance, or
  * <li>declare a only default constructor, in which case it will not receive parameters.
  * </ul>
+ * A generator must implement {@link #getEventTypes()} to specify the events for which it should be
+ * called to produce a new value. {@link EventTypeSets} provides a convenient list of possibilities.
+ * <p>
+ * An {@linkplain jakarta.persistence.Id identifier} generator is a generator capable of producing
+ * surrogate primary key values. An identifier generator must respond to insert events only. That
+ * is, {@link #getEventTypes()} must return {@link EventTypeSets#INSERT_ONLY}. It may be integrated
+ * using the {@link org.hibernate.annotations.IdGeneratorType} meta-annotation or the older-style
+ * {@link org.hibernate.annotations.GenericGenerator} annotation.
  *
  * @see org.hibernate.annotations.ValueGenerationType
  * @see org.hibernate.annotations.IdGeneratorType
@@ -57,11 +69,25 @@ public interface Generator extends Serializable {
 	 */
 	boolean generatedByDatabase();
 
-	boolean generatedOnInsert();
+	/**
+	 * The {@linkplain EventType event types} for which this generator should be called
+	 * to produce a new value.
+	 * <p>
+	 * Identifier generators must return {@link EventTypeSets#INSERT_ONLY}.
+	 *
+	 * @return a set of {@link EventType}s.
+	 */
+	EnumSet<EventType> getEventTypes();
 
-	boolean generatedOnUpdate();
+	default boolean generatesSometimes() {
+		return !getEventTypes().isEmpty();
+	}
 
-	default boolean isNotNever() {
+	default boolean generatesOnInsert() {
-		return generatedOnInsert() || generatedOnUpdate();
+		return getEventTypes().contains(INSERT);
+	}
+
+	default boolean generatesOnUpdate() {
+		return getEventTypes().contains(UPDATE);
 	}
 }

hibernate-core/src/main/java/org/hibernate/generator/InMemoryGenerator.java

@@ -7,7 +7,6 @@
 package org.hibernate.generator;
 
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
-import org.hibernate.tuple.GenerationTiming;
 
 /**
  * A generator that is called to produce a value just before a row is written to the database.
@@ -16,8 +15,8 @@ import org.hibernate.tuple.GenerationTiming;
  * database via a parameter of a JDBC prepared statement, just like any other field or property
  * value.
  * <p>
- * Any {@link InMemoryGenerator} with {@linkplain #getGenerationTiming() generation timing}
+ * Any {@link InMemoryGenerator} with {@linkplain #getEventTypes() generation event types}
- * {@link GenerationTiming#INSERT} may be used to produce {@linkplain jakarta.persistence.Id
+ * {@link EventTypeSets#INSERT_ONLY} may be used to produce {@linkplain jakarta.persistence.Id
  * identifiers}. The built-in identifier generators all implement the older extension point
  * {@link org.hibernate.id.IdentifierGenerator}, which is a subtype of this interface, but that
  * is no longer a requirement for custom id generators.

hibernate-core/src/main/java/org/hibernate/generator/internal/CurrentTimestampGeneration.java

@@ -10,22 +10,25 @@ import org.hibernate.AssertionFailure;
 import org.hibernate.Session;
 import org.hibernate.annotations.CreationTimestamp;
 import org.hibernate.annotations.CurrentTimestamp;
-import org.hibernate.annotations.GenerationTime;
 import org.hibernate.annotations.SourceType;
 import org.hibernate.annotations.UpdateTimestamp;
 import org.hibernate.dialect.Dialect;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.generator.EventType;
 import org.hibernate.generator.InDatabaseGenerator;
 import org.hibernate.generator.InMemoryGenerator;
 import org.hibernate.internal.util.ReflectHelper;
 import org.hibernate.generator.GeneratorCreationContext;
+import org.hibernate.tuple.GenerationTiming;
 import org.hibernate.tuple.TimestampGenerators;
 import org.hibernate.tuple.ValueGenerator;
 
 import java.lang.reflect.Member;
+import java.util.EnumSet;
 
-import static org.hibernate.annotations.GenerationTime.INSERT;
+import static org.hibernate.generator.EventTypeSets.INSERT_AND_UPDATE;
-import static org.hibernate.annotations.GenerationTime.INSERT_OR_UPDATE;
+import static org.hibernate.generator.EventTypeSets.INSERT_ONLY;
+import static org.hibernate.generator.EventTypeSets.fromArray;
 
 /**
  * Value generation strategy which produces a timestamp using the database
@@ -45,22 +48,24 @@ import static org.hibernate.annotations.GenerationTime.INSERT_OR_UPDATE;
  * @author Gavin King
  */
 public class CurrentTimestampGeneration implements InMemoryGenerator, InDatabaseGenerator {
-	private final GenerationTime timing;
+	private final EnumSet<EventType> eventTypes;
 	private final ValueGenerator<?> generator;
 
 	public CurrentTimestampGeneration(CurrentTimestamp annotation, Member member, GeneratorCreationContext context) {
 		generator = getGenerator( annotation.source(), member );
-		timing = annotation.event() == INSERT_OR_UPDATE ? annotation.timing().getEquivalent() : annotation.event();
+		eventTypes = annotation.timing() == GenerationTiming.ALWAYS
+				? fromArray( annotation.event() )
+				: annotation.timing().getEquivalent().eventTypes();
 	}
 
 	public CurrentTimestampGeneration(CreationTimestamp annotation, Member member, GeneratorCreationContext context) {
 		generator = getGenerator( annotation.source(), member );
-		timing = INSERT;
+		eventTypes = INSERT_ONLY;
 	}
 
 	public CurrentTimestampGeneration(UpdateTimestamp annotation, Member member, GeneratorCreationContext context) {
 		generator = getGenerator( annotation.source(), member );
-		timing = INSERT_OR_UPDATE;
+		eventTypes = INSERT_AND_UPDATE;
 	}
 
 	private static ValueGenerator<?> getGenerator(SourceType source, Member member) {
@@ -81,13 +86,8 @@ public class CurrentTimestampGeneration implements InMemoryGenerator, InDatabase
 	}
 
 	@Override
-	public boolean generatedOnInsert() {
+	public EnumSet<EventType> getEventTypes() {
-		return timing.includesInsert();
+		return eventTypes;
-	}
-
-	@Override
-	public boolean generatedOnUpdate() {
-		return timing.includesUpdate();
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/generator/internal/GeneratedAlwaysGeneration.java

@@ -8,8 +8,13 @@ package org.hibernate.generator.internal;
 
 import org.hibernate.annotations.GeneratedColumn;
 import org.hibernate.dialect.Dialect;
+import org.hibernate.generator.EventType;
 import org.hibernate.generator.InDatabaseGenerator;
 
+import java.util.EnumSet;
+
+import static org.hibernate.generator.EventTypeSets.ALL;
+
 /**
  * For {@link GeneratedColumn}.
  *
@@ -20,13 +25,8 @@ public class GeneratedAlwaysGeneration implements InDatabaseGenerator {
 	public GeneratedAlwaysGeneration() {}
 
 	@Override
-	public boolean generatedOnUpdate() {
+	public EnumSet<EventType> getEventTypes() {
-		return true;
+		return ALL;
-	}
-
-	@Override
-	public boolean generatedOnInsert() {
-		return true;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/generator/internal/GeneratedGeneration.java

@@ -9,45 +9,46 @@ package org.hibernate.generator.internal;
 import org.hibernate.annotations.Generated;
 import org.hibernate.annotations.GenerationTime;
 import org.hibernate.dialect.Dialect;
+import org.hibernate.generator.EventType;
 import org.hibernate.generator.InDatabaseGenerator;
-import org.hibernate.tuple.AnnotationValueGeneration;
 
-import static org.hibernate.annotations.GenerationTime.INSERT_OR_UPDATE;
+import java.util.EnumSet;
+
+import static org.hibernate.generator.EventTypeSets.fromArray;
 import static org.hibernate.internal.util.StringHelper.isEmpty;
 
 /**
- * A {@link AnnotationValueGeneration} which marks a property as generated in the database.
+ * A fairly generic {@link InDatabaseGenerator} which marks a property as generated in the
+ * database with semantics given explicitly by a {@link Generated @Generated} annotation.
+ *
+ * @see Generated
  *
  * @author Steve Ebersole
  * @author Gunnar Morling
  */
 public class GeneratedGeneration implements InDatabaseGenerator {
 
-	private GenerationTime timing;
+	private final EnumSet<EventType> eventTypes;
-	private boolean writable;
+	private final boolean writable;
-	private String[] sql;
+	private final String[] sql;
-
-	public GeneratedGeneration() {
-	}
 
 	public GeneratedGeneration(GenerationTime event) {
-		this.timing = event;
+		eventTypes = event.eventTypes();
+		writable = false;
+		sql = null;
 	}
 
 	public GeneratedGeneration(Generated annotation) {
-		timing = annotation.event() == INSERT_OR_UPDATE ? annotation.value() : annotation.event();
+		eventTypes = annotation.value() == GenerationTime.ALWAYS
+				? fromArray( annotation.event() )
+				: annotation.value().eventTypes();
 		sql = isEmpty( annotation.sql() ) ? null : new String[] { annotation.sql() };
 		writable = annotation.writable() || sql != null;
 	}
 
 	@Override
-	public boolean generatedOnInsert() {
+	public EnumSet<EventType> getEventTypes() {
-		return timing.includesInsert();
+		return eventTypes;
-	}
-
-	@Override
-	public boolean generatedOnUpdate() {
-		return timing.includesUpdate();
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/generator/internal/SourceGeneration.java

@@ -14,6 +14,8 @@ import org.hibernate.annotations.SourceType;
 import org.hibernate.dialect.Dialect;
 import org.hibernate.engine.jdbc.spi.JdbcCoordinator;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.generator.EventType;
+import org.hibernate.generator.EventTypeSets;
 import org.hibernate.generator.GeneratorCreationContext;
 import org.hibernate.generator.InMemoryGenerator;
 import org.hibernate.internal.CoreMessageLogger;
@@ -27,8 +29,10 @@ import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Timestamp;
+import java.util.EnumSet;
 
 import static java.sql.Types.TIMESTAMP;
+import static org.hibernate.generator.EventTypeSets.INSERT_ONLY;
 
 /**
  * Value generation strategy using the query {@link Dialect#getCurrentTimestampSelectString()}.
@@ -77,19 +81,11 @@ public class SourceGeneration implements InMemoryGenerator {
 	}
 
 	/**
-	 * @return {@code true}
+	 * @return {@link EventTypeSets#INSERT_ONLY}
 	 */
 	@Override
-	public boolean generatedOnInsert() {
+	public EnumSet<EventType> getEventTypes() {
-		return true;
+		return INSERT_ONLY;
-	}
-
-	/**
-	 * @return {@code false}
-	 */
-	@Override
-	public boolean generatedOnUpdate() {
-		return false;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/generator/internal/TenantIdGeneration.java

@@ -12,12 +12,16 @@ import org.hibernate.annotations.TenantId;
 import org.hibernate.context.spi.CurrentTenantIdentifierResolver;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.generator.EventType;
+import org.hibernate.generator.EventTypeSets;
 import org.hibernate.generator.InMemoryGenerator;
 import org.hibernate.generator.GeneratorCreationContext;
 import org.hibernate.type.descriptor.java.JavaType;
 
 import java.lang.reflect.Member;
+import java.util.EnumSet;
 
+import static org.hibernate.generator.EventTypeSets.INSERT_ONLY;
 import static org.hibernate.internal.util.ReflectHelper.getPropertyType;
 
 /**
@@ -39,19 +43,11 @@ public class TenantIdGeneration implements InMemoryGenerator {
 	}
 
 	/**
-	 * @return {@code true}
+	 * @return {@link EventTypeSets#INSERT_ONLY}
 	 */
 	@Override
-	public boolean generatedOnInsert() {
+	public EnumSet<EventType> getEventTypes() {
-		return true;
+		return INSERT_ONLY;
-	}
-
-	/**
-	 * @return {@code false}
-	 */
-	@Override
-	public boolean generatedOnUpdate() {
-		return false;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/id/IdentifierGenerator.java

@@ -6,6 +6,7 @@
  */
 package org.hibernate.id;
 
+import java.util.EnumSet;
 import java.util.Properties;
 
 import org.hibernate.HibernateException;
@@ -14,15 +15,18 @@ import org.hibernate.boot.model.relational.Database;
 import org.hibernate.boot.model.relational.ExportableProducer;
 import org.hibernate.boot.model.relational.SqlStringGenerationContext;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.generator.EventType;
+import org.hibernate.generator.EventTypeSets;
 import org.hibernate.service.ServiceRegistry;
-import org.hibernate.tuple.GenerationTiming;
 import org.hibernate.generator.InMemoryGenerator;
 import org.hibernate.type.Type;
 
+import static org.hibernate.generator.EventTypeSets.INSERT_ONLY;
+
 /**
  * A classic extension point from the very earliest days of Hibernate,
  * this interface is no longer the only way to generate identifiers. Any
- * {@link InMemoryGenerator} with timing {@link GenerationTiming#INSERT}
+ * {@link InMemoryGenerator} with timing {@link EventTypeSets#INSERT_ONLY}
  * may now be used.
  * <p>
  * This interface extends {@code InMemoryGenerator} with some additional
@@ -143,19 +147,11 @@ public interface IdentifierGenerator extends InMemoryGenerator, ExportableProduc
 	}
 
 	/**
-	 * @return {@code true}
+	 * @return {@link EventTypeSets#INSERT_ONLY}
 	 */
 	@Override
-	default boolean generatedOnInsert() {
+	default EnumSet<EventType> getEventTypes() {
-		return true;
+		return INSERT_ONLY;
-	}
-
-	/**
-	 * @return {@code false}
-	 */
-	@Override
-	default boolean generatedOnUpdate() {
-		return false;
 	}
 
 	/**

hibernate-core/src/main/java/org/hibernate/id/PostInsertIdentifierGenerator.java

@@ -6,17 +6,21 @@
  */
 package org.hibernate.id;
 
+import org.hibernate.generator.EventType;
+import org.hibernate.generator.EventTypeSets;
 import org.hibernate.service.ServiceRegistry;
-import org.hibernate.tuple.GenerationTiming;
 import org.hibernate.generator.InDatabaseGenerator;
 import org.hibernate.type.Type;
 
+import java.util.EnumSet;
 import java.util.Properties;
 
+import static org.hibernate.generator.EventTypeSets.INSERT_ONLY;
+
 /**
  * The counterpart of {@link IdentifierGenerator} for values generated by the database.
  * This interface is no longer the only way to handle database-generate identifiers.
- * Any {@link InDatabaseGenerator} with timing {@link GenerationTiming#INSERT} may now
+ * Any {@link InDatabaseGenerator} with timing {@link EventTypeSets#INSERT_ONLY} may now
  * be used.
  *
  * @see IdentifierGenerator
@@ -26,19 +30,11 @@ import java.util.Properties;
 public interface PostInsertIdentifierGenerator extends InDatabaseGenerator, Configurable {
 
 	/**
-	 * @return {@code true}
+	 * @return {@link EventTypeSets#INSERT_ONLY}
 	 */
 	@Override
-	default boolean generatedOnInsert() {
+	default EnumSet<EventType> getEventTypes() {
-		return true;
+		return INSERT_ONLY;
-	}
-
-	/**
-	 * @return {@code false}
-	 */
-	@Override
-	default boolean generatedOnUpdate() {
-		return false;
 	}
 
 	/**

hibernate-core/src/main/java/org/hibernate/id/uuid/UuidGenerator.java

@@ -7,16 +7,20 @@
 package org.hibernate.id.uuid;
 
 import java.lang.reflect.Member;
+import java.util.EnumSet;
 import java.util.UUID;
 
 import org.hibernate.HibernateException;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.generator.EventType;
+import org.hibernate.generator.EventTypeSets;
 import org.hibernate.id.factory.spi.CustomIdGeneratorCreationContext;
 import org.hibernate.generator.InMemoryGenerator;
 import org.hibernate.type.descriptor.java.UUIDJavaType;
 import org.hibernate.type.descriptor.java.UUIDJavaType.ValueTransformer;
 
 import static org.hibernate.annotations.UuidGenerator.Style.TIME;
+import static org.hibernate.generator.EventTypeSets.INSERT_ONLY;
 import static org.hibernate.internal.util.ReflectHelper.getPropertyType;
 
 /**
@@ -60,19 +64,11 @@ public class UuidGenerator implements InMemoryGenerator {
 	}
 
 	/**
-	 * @return {@code true}
+	 * @return {@link EventTypeSets#INSERT_ONLY}
 	 */
 	@Override
-	public boolean generatedOnInsert() {
+	public EnumSet<EventType> getEventTypes() {
-		return true;
+		return INSERT_ONLY;
-	}
-
-	/**
-	 * @return {@code false}
-	 */
-	@Override
-	public boolean generatedOnUpdate() {
-		return false;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/internal/GeneratedValuesProcessor.java

@@ -97,7 +97,7 @@ public class GeneratedValuesProcessor {
 			final Generator generator = generators[ mapping.getStateArrayPosition() ];
 			if ( generator != null
 					&& generator.generatedByDatabase()
-					&& generator.isNotNever() ) {
+					&& generator.generatesSometimes() ) {
 				// this attribute is generated for the timing we are processing...
 				valueDescriptors.add( new GeneratedValueDescriptor(
 						new InDatabaseGeneratedValueResolver( timing, generatedValuesToSelect.size() ),

hibernate-core/src/main/java/org/hibernate/persister/entity/AbstractEntityPersister.java

@@ -2773,7 +2773,7 @@ public abstract class AbstractEntityPersister
 					else {
 						final Generator generator = attributeMapping.getGenerator();
 						if ( generator!=null
-								&& generator.generatedOnUpdate()
+								&& generator.generatesOnUpdate()
 								&& generator.generatedByDatabase() ) {
 							final InDatabaseGenerator databaseGenerator = (InDatabaseGenerator) generator;
 							final Dialect dialect = getFactory().getJdbcServices().getDialect();

hibernate-core/src/main/java/org/hibernate/persister/entity/mutation/InsertCoordinator.java

@@ -106,7 +106,7 @@ public class InsertCoordinator extends AbstractMutationCoordinator {
 				Generator generator = generators[i];
 				if ( generator != null
 						&& !generator.generatedByDatabase()
-						&& generator.generatedOnInsert() ) {
+						&& generator.generatesOnInsert() ) {
 					values[i] = ( (InMemoryGenerator) generator ).generate( session, entity, values[i] );
 					entityPersister().setPropertyValue( entity, i, values[i] );
 				}
@@ -438,7 +438,7 @@ public class InsertCoordinator extends AbstractMutationCoordinator {
 
 	private static boolean isValueGenerationInSql(Generator generator, Dialect dialect) {
 		return generator != null
-			&& generator.generatedOnInsert()
+			&& generator.generatesOnInsert()
 			&& generator.generatedByDatabase()
 			&& ( (InDatabaseGenerator) generator ).referenceColumnsInSql(dialect);
 	}

hibernate-core/src/main/java/org/hibernate/persister/entity/mutation/UpdateCoordinatorStandard.java

@@ -337,14 +337,14 @@ public class UpdateCoordinatorStandard extends AbstractMutationCoordinator imple
 
 	private boolean isValueGenerationInSql(Generator generator, Dialect dialect) {
 		return generator != null
-			&& generator.generatedOnUpdate()
+			&& generator.generatesOnUpdate()
 			&& generator.generatedByDatabase()
 			&& ((InDatabaseGenerator) generator).referenceColumnsInSql(dialect);
 	}
 
 	private boolean isValueGenerationInSqlNoWrite(Generator generator, Dialect dialect) {
 		return generator != null
-			&& generator.generatedOnUpdate()
+			&& generator.generatesOnUpdate()
 			&& generator.generatedByDatabase()
 			&& ((InDatabaseGenerator) generator).referenceColumnsInSql(dialect)
 			&& !((InDatabaseGenerator) generator).writePropertyValue();
@@ -451,7 +451,7 @@ public class UpdateCoordinatorStandard extends AbstractMutationCoordinator imple
 				Generator generator = generators[i];
 				if ( generator != null
 						&& !generator.generatedByDatabase()
-						&& generator.generatedOnUpdate() ) {
+						&& generator.generatesOnUpdate() ) {
 					newValues[i] = ( (InMemoryGenerator) generator ).generate( session, object, newValues[i] );
 					entityPersister().setPropertyValue( object, i, newValues[i] );
 					fieldsPreUpdateNeeded[count++] = i;

hibernate-core/src/main/java/org/hibernate/tuple/GenerationTiming.java

@@ -84,7 +84,7 @@ public enum GenerationTiming {
 	public GenerationTime getEquivalent() {
 		switch (this) {
 			case ALWAYS:
-				return GenerationTime.INSERT_OR_UPDATE;
+				return GenerationTime.ALWAYS;
 			case INSERT:
 				return GenerationTime.INSERT;
 			case UPDATE:

hibernate-core/src/main/java/org/hibernate/tuple/ValueGeneration.java

@@ -9,10 +9,13 @@ package org.hibernate.tuple;
 import org.hibernate.Session;
 import org.hibernate.dialect.Dialect;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.generator.EventType;
 import org.hibernate.generator.Generator;
 import org.hibernate.generator.InDatabaseGenerator;
 import org.hibernate.generator.InMemoryGenerator;
 
+import java.util.EnumSet;
+
 /**
  * A value generator that can adapt to both Java value generation and database value generation.
  * <p>
@@ -39,13 +42,8 @@ public interface ValueGeneration extends InMemoryGenerator, InDatabaseGenerator
 	GenerationTiming getGenerationTiming();
 
 	@Override
-	default boolean generatedOnInsert() {
+	default EnumSet<EventType> getEventTypes() {
-		return getGenerationTiming().includesInsert();
+		return getGenerationTiming().getEquivalent().eventTypes();
-	}
-
-	@Override
-	default boolean generatedOnUpdate() {
-		return getGenerationTiming().includesUpdate();
 	}
 
 	/**

hibernate-core/src/main/java/org/hibernate/tuple/VmValueGeneration.java

@@ -7,13 +7,14 @@
 package org.hibernate.tuple;
 
 import java.lang.reflect.Constructor;
+import java.util.EnumSet;
 
 import org.hibernate.HibernateException;
 import org.hibernate.Internal;
 import org.hibernate.Session;
-import org.hibernate.annotations.GenerationTime;
 import org.hibernate.annotations.GeneratorType;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.generator.EventType;
 import org.hibernate.generator.InMemoryGenerator;
 
 import static org.hibernate.internal.util.ReflectHelper.getDefaultConstructor;
@@ -30,7 +31,7 @@ import static org.hibernate.internal.util.ReflectHelper.getDefaultConstructor;
 @Deprecated(since = "6.2")
 public class VmValueGeneration implements InMemoryGenerator {
 
-	private final GenerationTime timing;
+	private final EnumSet<EventType> eventTypes;
 	private final ValueGenerator<?> generator;
 
 	public VmValueGeneration(GeneratorType annotation) {
@@ -41,26 +42,14 @@ public class VmValueGeneration implements InMemoryGenerator {
 		catch (Exception e) {
 			throw new HibernateException( "Couldn't instantiate value generator", e );
 		}
-		timing = annotation.when();
+		eventTypes = annotation.when().eventTypes();
 	}
 
-	/**
-	 * @return {@code true}
-	 */
 	@Override
-	public boolean generatedOnInsert() {
+	public EnumSet<EventType> getEventTypes() {
-		return timing.includesInsert();
+		return eventTypes;
 	}
 
-	/**
-	 * @return {@code false}
-	 */
-	@Override
-	public boolean generatedOnUpdate() {
-		return timing.includesUpdate();
-	}
-
-
 	@Override
 	public Object generate(SharedSessionContractImplementor session, Object owner, Object currentValue) {
 		return generator.generateValue( (Session) session, owner, currentValue );

hibernate-core/src/main/java/org/hibernate/tuple/entity/EntityMetamodel.java

@@ -10,6 +10,7 @@ import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.BitSet;
 import java.util.Collections;
+import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -29,6 +30,7 @@ import org.hibernate.engine.spi.CascadeStyle;
 import org.hibernate.engine.spi.CascadeStyles;
 import org.hibernate.engine.spi.CascadingActions;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
+import org.hibernate.generator.EventType;
 import org.hibernate.internal.CoreMessageLogger;
 import org.hibernate.internal.util.ReflectHelper;
 import org.hibernate.internal.util.collections.ArrayHelper;
@@ -56,6 +58,7 @@ import org.hibernate.type.EntityType;
 import org.hibernate.type.ManyToOneType;
 import org.hibernate.type.Type;
 
+import static org.hibernate.generator.EventTypeSets.NONE;
 import static org.hibernate.internal.CoreLogging.messageLogger;
 
 /**
@@ -309,7 +312,7 @@ public class EntityMetamodel implements Serializable {
 					propertyInsertability[i] = false;
 					propertyUpdateability[i] = false;
 				}
-				if ( generator.generatedOnInsert() ) {
+				if ( generator.generatesOnInsert() ) {
 					if ( generator.generatedByDatabase() ) {
 						foundPostInsertGeneratedValues = true;
 					}
@@ -317,7 +320,7 @@ public class EntityMetamodel implements Serializable {
 						foundPreInsertGeneratedValues = true;
 					}
 				}
-				if ( generator.generatedOnUpdate() ) {
+				if ( generator.generatesOnUpdate() ) {
 					if ( generator.generatedByDatabase() ) {
 						foundPostUpdateGeneratedValues = true;
 					}
@@ -454,7 +457,7 @@ public class EntityMetamodel implements Serializable {
 		final GeneratorCreator generatorCreator = mappingProperty.getValueGeneratorCreator();
 		if ( generatorCreator != null ) {
 			final Generator generator = mappingProperty.createGenerator( context );
-			if ( generator.isNotNever() ) {
+			if ( generator.generatesSometimes() ) {
 				return generator;
 			}
 		}
@@ -510,7 +513,7 @@ public class EntityMetamodel implements Serializable {
 		}
 
 		private void add(InMemoryGenerator inMemoryStrategy) {
-			if ( inMemoryStrategy.isNotNever() ) {
+			if ( inMemoryStrategy.generatesSometimes() ) {
 				hadInMemoryGeneration = true;
 			}
 		}
@@ -521,7 +524,7 @@ public class EntityMetamodel implements Serializable {
 			}
 			inDatabaseStrategies.add( inDatabaseStrategy );
 
-			if ( inDatabaseStrategy.isNotNever() ) {
+			if ( inDatabaseStrategy.generatesSometimes() ) {
 				hadInDatabaseGeneration = true;
 			}
 		}
@@ -549,8 +552,7 @@ public class EntityMetamodel implements Serializable {
 				}
 
 				// the base-line values for the aggregated InDatabaseValueGenerationStrategy we will build here.
-				boolean generatedOnInsert = false;
+				EnumSet<EventType> eventTypes = EnumSet.noneOf(EventType.class);
-				boolean generatedOnUpdate = false;
 				boolean referenceColumns = false;
 				String[] columnValues = new String[ composite.getColumnSpan() ];
 
@@ -559,15 +561,14 @@ public class EntityMetamodel implements Serializable {
 				int columnIndex = 0;
 				for ( Property property : composite.getProperties() ) {
 					propertyIndex++;
-					final InDatabaseGenerator subStrategy = inDatabaseStrategies.get( propertyIndex );
+					final InDatabaseGenerator generator = inDatabaseStrategies.get( propertyIndex );
-					generatedOnUpdate = generatedOnUpdate || subStrategy.generatedOnUpdate();
+					eventTypes.addAll( generator.getEventTypes() );
-					generatedOnInsert = generatedOnInsert || subStrategy.generatedOnInsert();
+					if ( generator.referenceColumnsInSql(dialect) ) {
-					if ( subStrategy.referenceColumnsInSql(dialect) ) {
 						// override base-line value
 						referenceColumns = true;
 					}
-					if ( subStrategy.getReferencedColumnValues(dialect) != null ) {
+					if ( generator.getReferencedColumnValues(dialect) != null ) {
-						if ( subStrategy.getReferencedColumnValues(dialect).length != property.getColumnSpan() ) {
+						if ( generator.getReferencedColumnValues(dialect).length != property.getColumnSpan() ) {
 							throw new ValueGenerationStrategyException(
 									"Internal error : mismatch between number of collected 'referenced column values'" +
 											" and number of columns for composite attribute : " + mappingProperty.getName() +
@@ -575,7 +576,7 @@ public class EntityMetamodel implements Serializable {
 							);
 						}
 						System.arraycopy(
-								subStrategy.getReferencedColumnValues(dialect),
+								generator.getReferencedColumnValues(dialect),
 								0,
 								columnValues,
 								columnIndex,
@@ -585,19 +586,14 @@ public class EntityMetamodel implements Serializable {
 				}
 
 				// then use the aggregated values to build the InDatabaseValueGenerationStrategy
-				return new InDatabaseGeneratorImpl( generatedOnUpdate, generatedOnInsert, referenceColumns, columnValues );
+				return new InDatabaseGeneratorImpl( eventTypes, referenceColumns, columnValues );
 			}
 			else {
 				return new Generator() {
 					@Override
-					public boolean generatedOnInsert() {
+					public EnumSet<EventType> getEventTypes() {
-						return false;
+						return NONE;
 					}
-					@Override
-					public boolean generatedOnUpdate() {
-						return false;
-					}
-					@Override
 					public boolean generatedByDatabase() {
 						return false;
 					}
@@ -607,30 +603,22 @@ public class EntityMetamodel implements Serializable {
 	}
 
 	private static class InDatabaseGeneratorImpl implements InDatabaseGenerator {
-		private final boolean generatedOnUpdate;
+		private final EnumSet<EventType> eventTypes;
-		private final boolean generatedOnInsert;
 		private final boolean referenceColumnInSql;
 		private final String[] referencedColumnValues;
 
 		private InDatabaseGeneratorImpl(
-				boolean generatedOnUpdate,
+				EnumSet<EventType> eventTypes,
-				boolean generatedOnInsert,
 				boolean referenceColumnInSql,
 				String[] referencedColumnValues) {
-			this.generatedOnUpdate = generatedOnUpdate;
+			this.eventTypes = eventTypes;
-			this.generatedOnInsert = generatedOnInsert;
 			this.referenceColumnInSql = referenceColumnInSql;
 			this.referencedColumnValues = referencedColumnValues;
 		}
 
 		@Override
-		public boolean generatedOnInsert() {
+		public EnumSet<EventType> getEventTypes() {
-			return generatedOnInsert;
+			return eventTypes;
-		}
-
-		@Override
-		public boolean generatedOnUpdate() {
-			return generatedOnUpdate;
 		}
 
 		@Override
@@ -672,17 +660,17 @@ public class EntityMetamodel implements Serializable {
 		//		* That code checks that there is a natural identifier before making this call, so we assume the same here
 		// 		* That code assumes a non-composite natural-id, so we assume the same here
 		final Generator strategy = generators[ naturalIdPropertyNumbers[0] ];
-		return strategy != null && strategy.isNotNever();
+		return strategy != null && strategy.generatesSometimes();
 	}
 
 	public boolean isVersionGeneratedByDatabase() {
 		final Generator strategy = generators[ versionPropertyIndex ];
-		return strategy != null && strategy.isNotNever() && strategy.generatedByDatabase();
+		return strategy != null && strategy.generatesSometimes() && strategy.generatedByDatabase();
 	}
 
 	public boolean isVersionGeneratedInMemory() {
 		final Generator strategy = generators[ versionPropertyIndex ];
-		return strategy != null && strategy.isNotNever() && !strategy.generatedByDatabase();
+		return strategy != null && strategy.generatesSometimes() && !strategy.generatedByDatabase();
 	}
 
 	public int[] getNaturalIdentifierProperties() {

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/generated/CurrentTimestampAnnotationTests.java

@@ -22,8 +22,8 @@ import org.hibernate.testing.orm.junit.SessionFactoryScope;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.hibernate.annotations.GenerationTime.INSERT;
+import static org.hibernate.generator.EventType.INSERT;
-import static org.hibernate.annotations.GenerationTime.INSERT_OR_UPDATE;
+import static org.hibernate.generator.EventType.UPDATE;
 
 /**
  * @author Steve Ebersole
@@ -66,9 +66,7 @@ public class CurrentTimestampAnnotationTests {
 		waitALittle();
 
 		// lastly, make sure we can load it..
-		final AuditedEntity loaded = scope.fromTransaction( (session) -> {
+		final AuditedEntity loaded = scope.fromTransaction( (session) -> session.get( AuditedEntity.class, 1 ) );
-			return session.get( AuditedEntity.class, 1 );
-		} );
 
 		assertThat( loaded ).isNotNull();
 		assertThat( loaded.createdAt ).isEqualTo( merged.createdAt );
@@ -86,7 +84,7 @@ public class CurrentTimestampAnnotationTests {
 		@CurrentTimestamp(event = INSERT)
 		public Instant createdAt;
 
-		@CurrentTimestamp(event = INSERT_OR_UPDATE)
+		@CurrentTimestamp(event = {INSERT, UPDATE})
 		public Instant lastUpdatedAt;
 		//end::mapping-generated-CurrentTimestamp-ex1[]
 

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/generated/temporals/GeneratedUuidTests.java

@@ -11,6 +11,7 @@ import java.lang.annotation.Inherited;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
+import java.util.EnumSet;
 import java.util.UUID;
 import jakarta.persistence.Basic;
 import jakarta.persistence.Entity;
@@ -19,6 +20,7 @@ import jakarta.persistence.Table;
 
 import org.hibernate.annotations.ValueGenerationType;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
+import org.hibernate.generator.EventType;
 import org.hibernate.tuple.GenerationTiming;
 import org.hibernate.generator.InMemoryGenerator;
 
@@ -84,20 +86,15 @@ public class GeneratedUuidTests {
 
 	//tag::mapping-generated-custom-ex3[]
 	public static class UuidValueGeneration implements InMemoryGenerator {
-		private final GenerationTiming timing;
+		private final EnumSet<EventType> eventTypes;
 
 		public UuidValueGeneration(GeneratedUuidValue annotation) {
-			timing = annotation.timing();
+			eventTypes = annotation.timing().getEquivalent().eventTypes();
 		}
 
 		@Override
-		public boolean generatedOnInsert() {
+		public EnumSet<EventType> getEventTypes() {
-			return timing.includesInsert();
+			return eventTypes;
-		}
-
-		@Override
-		public boolean generatedOnUpdate() {
-			return timing.includesUpdate();
 		}
 
 		@Override

hibernate-envers/src/main/java/org/hibernate/envers/configuration/internal/metadata/AuditMetadataGenerator.java

@@ -123,7 +123,7 @@ public final class AuditMetadataGenerator extends AbstractMetadataGenerator {
 			final GeneratorCreator generation = property.getValueGeneratorCreator();
 			if ( generation instanceof GeneratedGeneration) {
 				final GeneratedGeneration valueGeneration = (GeneratedGeneration) generation;
-				if ( valueGeneration.generatedOnInsert() ) {
+				if ( valueGeneration.generatesOnInsert() ) {
 					return true;
 				}
 			}
@@ -189,7 +189,6 @@ public final class AuditMetadataGenerator extends AbstractMetadataGenerator {
 		}
 	}
 
-	@SuppressWarnings("unchecked")
 	private void addJoins(
 			PersistentClass persistentClass,
 			CompositeMapperBuilder currentMapper,