HHH-7377 - NullPointerException in conjunction with natural IDs after Session.clear()

(cherry picked from commit 785e2d869e0141e3f1b120667d0e612906b73274)

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

@@ -2092,6 +2092,15 @@ public void handleSynchronization(EntityPersister persister, Serializable pk, Ob
 		public void cleanupFromSynchronizations() {
 			naturalIdXrefDelegate.unStashInvalidNaturalIdReferences();
 		}
+
+		@Override
+		public void handleEviction(Object object, EntityPersister persister, Serializable identifier) {
+			naturalIdXrefDelegate.removeNaturalIdCrossReference(
+					persister,
+					identifier,
+					findCachedNaturalId( persister, identifier )
+			);
+		}
 	};
 
 	@Override

hibernate-core/src/main/java/org/hibernate/engine/spi/PersistenceContext.java

@@ -830,6 +830,15 @@ public void manageSharedNaturalIdCrossReference(
 		 * of old values as no longer valid.
 		 */
 		public void cleanupFromSynchronizations();
+
+		/**
+		 * Called on {@link org.hibernate.Session#evict} to give a chance to clean up natural-id cross refs.
+		 *
+		 * @param object The entity instance.
+		 * @param persister The entity persister
+		 * @param identifier The entity identifier
+		 */
+		public void handleEviction(Object object, EntityPersister persister, Serializable identifier);
 	}
 
 	/**

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

@@ -80,7 +80,7 @@ public void onEvict(EvictEvent event) throws HibernateException {
 			if ( !li.isUninitialized() ) {
 				final Object entity = persistenceContext.removeEntity( key );
 				if ( entity != null ) {
-					EntityEntry e = event.getSession().getPersistenceContext().removeEntry( entity );
+					EntityEntry e = persistenceContext.removeEntry( entity );
 					doEvict( entity, key, e.getPersister(), event.getSession() );
 				}
 			}
@@ -106,6 +106,10 @@ protected void doEvict(
 			LOG.tracev( "Evicting {0}", MessageHelper.infoString( persister ) );
 		}
 
+		if ( persister.hasNaturalIdentifier() ) {
+			session.getPersistenceContext().getNaturalIdHelper().handleEviction( object, persister, key.getIdentifier() );
+		}
+
 		// remove all collections for the entity from the session-level cache
 		if ( persister.hasCollections() ) {
 			new EvictVisitor( session ).process( object, persister );

hibernate-core/src/main/java/org/hibernate/internal/SessionImpl.java

@@ -2491,12 +2491,12 @@ protected void performAnyNeededCrossReferenceSynchronizations() {
 				// synchronization (this process) was disabled
 				return;
 			}
-			if ( ! isTransactionInProgress() ) {
+			if ( entityPersister.getEntityMetamodel().hasImmutableNaturalId() ) {
-				// not in a transaction so skip synchronization
+				// only mutable natural-ids need this processing
 				return;
 			}
-			if ( entityPersister.getEntityMetamodel().hasImmutableNaturalId() ) {
+			if ( ! isTransactionInProgress() ) {
-				// only mutable natural-ids need this processing 
+				// not in a transaction so skip synchronization
 				return;
 			}
 
@@ -2505,6 +2505,16 @@ protected void performAnyNeededCrossReferenceSynchronizations() {
 				final Object entity = getPersistenceContext().getEntity( entityKey );
 				final EntityEntry entry = getPersistenceContext().getEntry( entity );
 
+				if ( entry == null ) {
+					if ( LOG.isDebugEnabled() ) {
+						LOG.debug(
+								"Cached natural-id/pk resolution linked to null EntityEntry in persistence context : "
+										+ MessageHelper.infoString( entityPersister, pk, getFactory() )
+						);
+					}
+					continue;
+				}
+
 				if ( !entry.requiresDirtyCheck( entity ) ) {
 					continue;
 				}

hibernate-core/src/test/java/org/hibernate/test/naturalid/mutable/MutableNaturalIdTest.java

@@ -472,4 +472,58 @@ public void testQuerying() throws Exception {
 		t.commit();
 		s.close();
 	}
+
+	@Test
+	public void testClear() {
+		Session s = openSession();
+		s.beginTransaction();
+		User u = new User( "steve", "hb", "superSecret" );
+		s.persist( u );
+		s.getTransaction().commit();
+		s.close();
+
+		s = openSession();
+		s.beginTransaction();
+		u = (User) session.byNaturalId( User.class )
+				.using( "name", "steve" )
+				.using( "org", "hb" )
+				.load();
+		assertNotNull( u );
+		s.clear();
+		u = (User) session.byNaturalId( User.class )
+				.using( "name", "steve" )
+				.using( "org", "hb" )
+				.load();
+		assertNotNull( u );
+		s.delete( u );
+		s.getTransaction().commit();
+		s.close();
+	}
+
+	@Test
+	public void testEviction() {
+		Session s = openSession();
+		s.beginTransaction();
+		User u = new User( "steve", "hb", "superSecret" );
+		s.persist( u );
+		s.getTransaction().commit();
+		s.close();
+
+		s = openSession();
+		s.beginTransaction();
+		u = (User) session.byNaturalId( User.class )
+				.using( "name", "steve" )
+				.using( "org", "hb" )
+				.load();
+		assertNotNull( u );
+		s.evict( u );
+		u = (User) session.byNaturalId( User.class )
+				.using( "name", "steve" )
+				.using( "org", "hb" )
+				.load();
+		assertNotNull( u );
+		s.delete( u );
+		s.getTransaction().commit();
+		s.close();
+	}
 }