HHH-16812 StackOverflowError an embeddable's @Parent is a subclass in an inheritance tree

hibernate-core/src/main/java/org/hibernate/PropertySetterAccessException.java

@@ -8,6 +8,8 @@ package org.hibernate;
 
 import java.util.Collection;
 
+import org.hibernate.proxy.HibernateProxy;
+
 /**
  * @author Steve Ebersole
  */
@@ -47,7 +49,7 @@ public class PropertySetterAccessException extends PropertyAccessException {
 	}
 
 	public static String loggablePropertyValueString(Object value) {
-		if ( value instanceof Collection ) {
+		if ( value instanceof Collection || value instanceof HibernateProxy ) {
 			return value.getClass().getSimpleName();
 		}
 		return value.toString();

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

@@ -375,6 +375,17 @@ public final class ManagedTypeHelper {
 		throw new ClassCastException( "Object of type '" + entity.getClass() + "' can't be cast to SelfDirtinessTracker" );
 	}
 
+	/**
+	 * Cast the object to an HibernateProxy, or return null in case it is not an instance of HibernateProxy
+	 * @param entity the entity to cast
+	 * @return the same instance after casting or null if it is not an instance of HibernateProxy
+	 */
+	public static HibernateProxy asHibernateProxyOrNull(final Object entity) {
+		return entity instanceof PrimeAmongSecondarySupertypes ?
+				( (PrimeAmongSecondarySupertypes) entity ).asHibernateProxy() :
+				null;
+	}
+
 	private static final class TypeMeta {
 		final boolean isManagedType;
 		final boolean isSelfDirtinessTrackerType;

hibernate-core/src/main/java/org/hibernate/sql/results/graph/embeddable/AbstractEmbeddableInitializer.java

@@ -6,6 +6,7 @@
  */
 package org.hibernate.sql.results.graph.embeddable;
 
+import org.hibernate.engine.internal.ManagedTypeHelper;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.metamodel.mapping.CompositeIdentifierMapping;
 import org.hibernate.metamodel.mapping.EmbeddableMappingType;
@@ -372,7 +373,8 @@ public abstract class AbstractEmbeddableInitializer extends AbstractFetchParentA
 			return;
 		}
 
-		final Object parent = determineParentInstance( processingState );
+		Initializer parentInitializer = determineParentInitializer( processingState );
+		final Object parent = determineParentInstance( parentInitializer );
 		if ( parent == null ) {
 			EmbeddableLoadingLogger.EMBEDDED_LOAD_LOGGER.debugf(
 					"Unable to determine parent for injection into embeddable [%s]",
@@ -388,10 +390,27 @@ public abstract class AbstractEmbeddableInitializer extends AbstractFetchParentA
 				compositeInstance
 		);
 
-		parentInjectionAccess.getSetter().set( compositeInstance, parent );
+
+		final HibernateProxy proxy;
+		if ( fetchParentAccess != null
+				&& ( proxy = ManagedTypeHelper.asHibernateProxyOrNull( parent ) ) != null ) {
+			assert parentInitializer != null;
+			assert parentInitializer instanceof EntityInitializer;
+			parentInitializer.asEntityInitializer().registerResolutionListener(
+					o ->
+							parentInjectionAccess.getSetter()
+									.set(
+											compositeInstance,
+											proxy.getHibernateLazyInitializer().getImplementation()
+									)
+			);
+		}
+		else {
+			parentInjectionAccess.getSetter().set( compositeInstance, parent );
+		}
 	}
 
-	private Object determineParentInstance(RowProcessingState processingState) {
+	private Initializer determineParentInitializer(RowProcessingState processingState){
 		// use `fetchParentAccess` if it is available - it is more efficient
 		// and the correct way to do it.
 
@@ -409,8 +428,7 @@ public abstract class AbstractEmbeddableInitializer extends AbstractFetchParentA
 			// todo (6.x) - allow injection of containing composite as parent if
 			//  	it is the direct parent
 
-			final FetchParentAccess firstEntityDescriptorAccess = fetchParentAccess.findFirstEntityDescriptorAccess();
-			return firstEntityDescriptorAccess.getInitializedInstance();
+			return fetchParentAccess.findFirstEntityDescriptorAccess();
 		}
 
 		// Otherwise, fallback to determining the parent-initializer by path
@@ -418,11 +436,15 @@ public abstract class AbstractEmbeddableInitializer extends AbstractFetchParentA
 		//			comment above
 
 		final NavigablePath parentPath = navigablePath.getParent();
-		if ( parentPath == null ) {
-			return null;
-		}
+		assert parentPath != null;
 
-		final Initializer parentInitializer = processingState.resolveInitializer( parentPath );
+		return processingState.resolveInitializer( parentPath );
+	}
+
+	private Object determineParentInstance(Initializer parentInitializer) {
+		if ( parentInitializer == null ) {
+			throw new UnsupportedOperationException( "Cannot determine Embeddable: " + navigablePath + " parent instance, parent initializer is null" );
+		}
 
 		if ( parentInitializer.isCollectionInitializer() ) {
 			return ( (CollectionInitializer) parentInitializer ).getCollectionInstance().getOwner();
@@ -430,10 +452,10 @@ public abstract class AbstractEmbeddableInitializer extends AbstractFetchParentA
 
 		final EntityInitializer parentEntityInitializer = parentInitializer.asEntityInitializer();
 		if ( parentEntityInitializer != null ) {
-			return parentEntityInitializer.getEntityInstance();
+			return parentEntityInitializer.getInitializedInstance();
 		}
 
-		throw new UnsupportedOperationException();
+		throw new UnsupportedOperationException( "The Embeddable: " + navigablePath + " parent initializer is neither an instance of an EntityInitializer nor of a CollectionInitializer" );
 	}
 
 	@Override