/*
 * Copyright (c) 1998, 2021 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle - initial API and implementation from Oracle TopLink
//     07/19/2011-2.2.1 Guy Pelletier
//       - 338812: ManyToMany mapping in aggregate object violate integrity constraint on deletion
//      //     30/05/2012-2.4 Guy Pelletier
//       - 354678: Temp classloader is still being used during metadata processing
package org.eclipse.persistence.mappings;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.eclipse.persistence.descriptors.changetracking.ChangeTracker;
import org.eclipse.persistence.descriptors.changetracking.CollectionChangeEvent;
import org.eclipse.persistence.descriptors.changetracking.MapChangeEvent;
import org.eclipse.persistence.exceptions.DatabaseException;
import org.eclipse.persistence.exceptions.DescriptorException;
import org.eclipse.persistence.exceptions.ValidationException;
import org.eclipse.persistence.expressions.Expression;
import org.eclipse.persistence.expressions.ExpressionBuilder;
import org.eclipse.persistence.indirection.IndirectCollection;
import org.eclipse.persistence.indirection.ValueHolder;
import org.eclipse.persistence.internal.descriptors.DescriptorIterator;
import org.eclipse.persistence.internal.descriptors.ObjectBuilder;
import org.eclipse.persistence.internal.descriptors.changetracking.AttributeChangeListener;
import org.eclipse.persistence.internal.descriptors.changetracking.ObjectChangeListener;
import org.eclipse.persistence.internal.expressions.SQLDeleteStatement;
import org.eclipse.persistence.internal.expressions.SQLSelectStatement;
import org.eclipse.persistence.internal.helper.ClassConstants;
import org.eclipse.persistence.internal.helper.DatabaseField;
import org.eclipse.persistence.internal.helper.Helper;
import org.eclipse.persistence.internal.identitymaps.CacheKey;
import org.eclipse.persistence.internal.indirection.TransparentIndirectionPolicy;
import org.eclipse.persistence.internal.queries.ContainerPolicy;
import org.eclipse.persistence.internal.queries.JoinedAttributeManager;
import org.eclipse.persistence.internal.queries.MappedKeyMapContainerPolicy;
import org.eclipse.persistence.internal.sessions.AbstractRecord;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import org.eclipse.persistence.internal.sessions.ChangeRecord;
import org.eclipse.persistence.internal.sessions.DirectMapChangeRecord;
import org.eclipse.persistence.internal.sessions.MergeManager;
import org.eclipse.persistence.internal.sessions.ObjectChangeSet;
import org.eclipse.persistence.internal.sessions.UnitOfWorkImpl;
import org.eclipse.persistence.mappings.converters.Converter;
import org.eclipse.persistence.mappings.converters.ObjectTypeConverter;
import org.eclipse.persistence.mappings.converters.SerializedObjectConverter;
import org.eclipse.persistence.mappings.converters.TypeConversionConverter;
import org.eclipse.persistence.mappings.foundation.MapComponentMapping;
import org.eclipse.persistence.queries.DataReadQuery;
import org.eclipse.persistence.queries.DatabaseQuery;
import org.eclipse.persistence.queries.DeleteObjectQuery;
import org.eclipse.persistence.queries.DirectReadQuery;
import org.eclipse.persistence.queries.ObjectBuildingQuery;
import org.eclipse.persistence.queries.ReadAllQuery;
import org.eclipse.persistence.queries.WriteObjectQuery;
import org.eclipse.persistence.sessions.DatabaseRecord;

/**
 * Mapping for a collection of key-value pairs.
 * The key and value must be simple types (String, Number, Date, etc.)
 * and stored in a single table along with a foreign key to the source object.
 * A converter can be used on the key and value if the desired object types
 * do not match the data types.
 *
 * @see Converter
 * @see ObjectTypeConverter
 * @see TypeConversionConverter
 * @see SerializedObjectConverter
 *
 * @author Steven Vo
 * @since TopLink 3.5
 */
public class DirectMapMapping extends DirectCollectionMapping implements MapComponentMapping {

    /**
     * DirectMapCollectionMapping constructor
     */
    public DirectMapMapping() {
        super();
        DataReadQuery query = new DataReadQuery();
        this.selectionQuery = query;
        MappedKeyMapContainerPolicy mapPolicy = new MappedKeyMapContainerPolicy(ClassConstants.Hashtable_Class);
        mapPolicy.setValueMapping(this);
        this.containerPolicy = mapPolicy;
        this.isListOrderFieldSupported = false;
    }

    /**
     * ADVANCED:
     * Configure the mapping to use a container policy.
     * This must be a MappedKeyMapContainerPolicy policy.
     * Set the valueMapping for the policy.
     */
    @Override
    public void setContainerPolicy(ContainerPolicy containerPolicy) {
        super.setContainerPolicy(containerPolicy);
        ((MappedKeyMapContainerPolicy)containerPolicy).setValueMapping(this);
    }

    private MappedKeyMapContainerPolicy getMappedKeyMapContainerPolicy(){
        return (MappedKeyMapContainerPolicy)containerPolicy;
    }

    /**
     * PUBLIC:
     * Return the converter on the mapping.
     * A converter can be used to convert between the key's object value and database value.
     */
    public Converter getKeyConverter() {
        return getMappedKeyMapContainerPolicy().getKeyConverter();
    }

    /**
     * PUBLIC:
     * Set the converter on the mapping.
     * A converter can be used to convert between the key's object value and database value.
     */
    public void setKeyConverter(Converter keyConverter) {
        getMappedKeyMapContainerPolicy().setKeyConverter(keyConverter, this);
    }

    /**
     * INTERNAL:
     * Set the converter class name on the mapping. Initialized in
     * convertClassNamesToClasses.
     * A converter can be used to convert between the key's object value and database value.
     */
    public void setKeyConverterClassName(String keyConverterClassName) {
        getMappedKeyMapContainerPolicy().setKeyConverterClassName(keyConverterClassName, this);
    }

    /**
     * INTERNAL:
     * Add a new value and its change set to the collection change record.  This is used by
     * attribute change tracking.  If a value has changed then issue a remove first with the key
     * then an add.
     */
    public void addToCollectionChangeRecord(Object newKey, Object newValue, ObjectChangeSet objectChangeSet, UnitOfWorkImpl uow) throws DescriptorException {
        DirectMapChangeRecord collectionChangeRecord = (DirectMapChangeRecord)objectChangeSet.getChangesForAttributeNamed(this.getAttributeName());
        if (collectionChangeRecord == null) {
            collectionChangeRecord = new DirectMapChangeRecord(objectChangeSet);
            collectionChangeRecord.setAttribute(getAttributeName());
            collectionChangeRecord.setMapping(this);
            objectChangeSet.addChange(collectionChangeRecord);
        }
        collectionChangeRecord.addAdditionChange(newKey, newValue);
    }

    /**
     * INTERNAL:
     * Require for cloning, the part must be cloned.
     * Ignore the objects, use the attribute value.
     */
    @Override
    public Object buildCloneForPartObject(Object attributeValue, Object original, CacheKey cacheKey, Object clone, AbstractSession cloningSession, Integer refreshCascade, boolean isExisting, boolean isFromSharedCache) {
        if (attributeValue == null) {
            return containerPolicy.containerInstance(1);
        }
        Object clonedAttributeValue = containerPolicy.containerInstance(containerPolicy.sizeFor(attributeValue));

        // I need to synchronize here to prevent the collection from changing while I am cloning it.
        // This will occur when I am merging into the cache and I am instantiating a UOW valueHolder at the same time
        // I can not synchronize around the clone, as this will cause deadlocks, so I will need to copy the collection then create the clones
        // I will use a temporary collection to help speed up the process
        Object temporaryCollection = null;
        synchronized (attributeValue) {
            temporaryCollection = containerPolicy.cloneFor(attributeValue);
        }

        for (Object keysIterator = containerPolicy.iteratorFor(temporaryCollection);
                 containerPolicy.hasNext(keysIterator);) {
            Map.Entry entry = (Map.Entry)containerPolicy.nextEntry(keysIterator, cloningSession);
            Object cloneKey = containerPolicy.buildCloneForKey(entry.getKey(), clone, cacheKey, null, cloningSession, isExisting, isFromSharedCache);
            Object cloneValue = buildElementClone(entry.getValue(), clone, cacheKey, refreshCascade, cloningSession, isExisting, isFromSharedCache);
            containerPolicy.addInto(cloneKey, cloneValue, clonedAttributeValue, cloningSession);
        }
        return clonedAttributeValue;
    }

    /**
     * INTERNAL:
     * Used by AttributeLevelChangeTracking to update a changeRecord with calculated changes
     * as opposed to detected changes.  If an attribute can not be change tracked it's
     * changes can be detected through this process.
     */
    @Override
    public void calculateDeferredChanges(ChangeRecord changeRecord, AbstractSession session) {
        DirectMapChangeRecord collectionRecord = (DirectMapChangeRecord)changeRecord;
        // TODO: Handle events that fired after collection was replaced.
        compareCollectionsForChange(collectionRecord.getOriginalCollection(), collectionRecord.getLatestCollection(), collectionRecord, session);
    }


    /**
     * INTERNAL:
     * Cascade discover and persist new objects during commit.
     */
    @Override
    public void cascadeDiscoverAndPersistUnregisteredNewObjects(Object object, Map newObjects, Map unregisteredExistingObjects, Map visitedObjects, UnitOfWorkImpl uow, Set cascadeErrors) {
        if (containerPolicy.isMappedKeyMapPolicy()){
            Object values = getAttributeValueFromObject(object);
            if (values != null){
                Object iterator = containerPolicy.iteratorFor(values);
                while (containerPolicy.hasNext(iterator)){
                    Object wrappedObject = containerPolicy.nextEntry(iterator, uow);
                    containerPolicy.cascadeDiscoverAndPersistUnregisteredNewObjects(wrappedObject, newObjects, unregisteredExistingObjects, visitedObjects, uow, cascadeErrors);
                }
            }
        }
    }

    /**
     * INTERNAL:
     * Cascade perform delete through mappings that require the cascade
     */
    @Override
    public void cascadePerformRemoveIfRequired(Object object, UnitOfWorkImpl uow, Map visitedObjects) {
        if (containerPolicy.isMappedKeyMapPolicy()){
            Object values = getAttributeValueFromObject(object);
            if (values != null){
                Object iterator = containerPolicy.iteratorFor(values);
                while (containerPolicy.hasNext(iterator)){
                    Object wrappedObject = containerPolicy.nextEntry(iterator, uow);
                    containerPolicy.cascadePerformRemoveIfRequired(wrappedObject, uow, visitedObjects);
                }
            }
        }
    }

    /**
     * INTERNAL:
     * Cascade registerNew for Create through mappings that require the cascade
     */
    @Override
    public void cascadeRegisterNewIfRequired(Object object, UnitOfWorkImpl uow, Map visitedObjects) {
        if (containerPolicy.isMappedKeyMapPolicy()){
            Object values = getAttributeValueFromObject(object);
            if (values != null){
                Object iterator = containerPolicy.iteratorFor(values);
                while (containerPolicy.hasNext(iterator)){
                    Object wrappedObject = containerPolicy.nextEntry(iterator, uow);
                    containerPolicy.cascadeRegisterNewIfRequired(wrappedObject, uow, visitedObjects);
                }
            }
        }
    }

    /**
     * INTERNAL:
     * This method is used to calculate the differences between two collections.
     */
    @Override
    public void compareCollectionsForChange(Object oldCollection, Object newCollection, ChangeRecord changeRecord, AbstractSession session) {
        HashMap originalKeyValues = new HashMap(10);
        HashMap cloneKeyValues = new HashMap(10);

        if (oldCollection != null) {
            Map backUpCollection = (Map)oldCollection;
            Object backUpIter = containerPolicy.iteratorFor(backUpCollection);
            while (containerPolicy.hasNext(backUpIter)) {// Make a lookup of the objects
                Map.Entry entry = (Map.Entry)containerPolicy.nextEntry(backUpIter, session);
                originalKeyValues.put(entry.getKey(), backUpCollection.get(entry.getKey()));
            }
        }

        Map cloneObjectCollection = (Map)newCollection;
        Object cloneIter = containerPolicy.iteratorFor(cloneObjectCollection);
        while (containerPolicy.hasNext(cloneIter)) {//Compare them with the objects from the clone
            Map.Entry wrappedFirstObject = (Map.Entry)containerPolicy.nextEntry(cloneIter, session);
            Object firstValue = wrappedFirstObject.getValue();
            Object firstKey = wrappedFirstObject.getKey();
            Object backupValue = originalKeyValues.get(firstKey);
            if (!originalKeyValues.containsKey(firstKey)) {
                cloneKeyValues.put(firstKey, cloneObjectCollection.get(firstKey));
            } else if (((backupValue == null) && (firstValue != null)) || (!backupValue.equals(firstValue))) {//the object was not in the backup
                cloneKeyValues.put(firstKey, cloneObjectCollection.get(firstKey));
            } else {
                originalKeyValues.remove(firstKey);
            }
        }

        ((DirectMapChangeRecord)changeRecord).clearChanges();
        ((DirectMapChangeRecord)changeRecord).addAdditionChange(cloneKeyValues);
        ((DirectMapChangeRecord)changeRecord).addRemoveChange(originalKeyValues);
        ((DirectMapChangeRecord)changeRecord).setIsDeferred(false);
        ((DirectMapChangeRecord)changeRecord).setLatestCollection(null);
    }

    /**
     * INTERNAL:
     * This method compares the changes between two direct collections.  Comparisons are made on equality
     * not identity.
     */
    @Override
    public ChangeRecord compareForChange(Object clone, Object backUp, ObjectChangeSet owner, AbstractSession session) {
        Object cloneAttribute = null;
        Object backUpAttribute = null;

        cloneAttribute = getAttributeValueFromObject(clone);
        if ((cloneAttribute != null) && (!getIndirectionPolicy().objectIsInstantiated(cloneAttribute))) {
            return null;
        }

        Map cloneObjectCollection = (Map)getRealCollectionAttributeValueFromObject(clone, session);

        Map backUpCollection = null;

        if (!owner.isNew()) {
            backUpAttribute = getAttributeValueFromObject(backUp);
            if ((backUpAttribute == null) && (cloneAttribute == null)) {
                return null;
            }
            backUpCollection = (Map)getRealCollectionAttributeValueFromObject(backUp, session);
        }

        DirectMapChangeRecord changeRecord = new DirectMapChangeRecord(owner);
        changeRecord.setAttribute(getAttributeName());
        changeRecord.setMapping(this);
        compareCollectionsForChange(backUpCollection, cloneObjectCollection, changeRecord, session);
        if (changeRecord.hasChanges()) {
            changeRecord.setOriginalCollection(backUpCollection);
            return changeRecord;
        }
        return null;
    }

    /**
     * INTERNAL:
     * Compare the attributes belonging to this mapping for the objects.
     */
    @Override
    public boolean compareObjects(Object firstObject, Object secondObject, AbstractSession session) {
        Object firstObjectMap = getRealCollectionAttributeValueFromObject(firstObject, session);
        Object secondObjectMap = getRealCollectionAttributeValueFromObject(secondObject, session);
        return getMappedKeyMapContainerPolicy().compareContainers(firstObjectMap, secondObjectMap);
    }

    /*
     * INTERNAL:
     * Convert all the class-name-based settings in this mapping to actual
     * class-based settings. This method is implemented by subclasses as
     * necessary.
     * @param classLoader
     */
    @Override
    public void convertClassNamesToClasses(ClassLoader classLoader) {
        super.convertClassNamesToClasses(classLoader);

        if (getDirectKeyField() != null) {
            getDirectKeyField().convertClassNamesToClasses(classLoader);
        }
    }

    /**
     * INTERNAL
     * Called when a DatabaseMapping is used to map the key in a collection.  Returns the key.
     */
    @Override
    public Object createMapComponentFromRow(AbstractRecord dbRow, ObjectBuildingQuery query, CacheKey parentCacheKey, AbstractSession session, boolean isTargetProtected){
        Object key = dbRow.get(getDirectField());
        if (getValueConverter() != null){
            key = getValueConverter().convertDataValueToObjectValue(key, session);
        }
        return key;
    }

    /**
     * INTERNAL:
     */
    public DatabaseField getDirectKeyField() {
        return getMappedKeyMapContainerPolicy().getDirectKeyField(null);
    }

    /**
     * INTERNAL:
     * Initialize and validate the mapping properties.
     */
    @Override
    public void initialize(AbstractSession session) throws DescriptorException {
        getMappedKeyMapContainerPolicy().setDescriptorForKeyMapping(this.getDescriptor());
        if (getKeyConverter() != null) {
            getKeyConverter().initialize(this, session);
        }
        super.initialize(session);
    }

    @Override
    protected void initializeDeleteQuery(AbstractSession session) {
        if (!getDeleteQuery().hasSessionName()) {
            getDeleteQuery().setSessionName(session.getName());
        }

        if (hasCustomDeleteQuery()) {
            return;
        }

        Expression builder = new ExpressionBuilder();
        Expression directKeyExp = null;
        List<DatabaseField> identityFields = getContainerPolicy().getIdentityFieldsForMapKey();
        Iterator<DatabaseField> i = identityFields.iterator();
        while (i.hasNext()){
            DatabaseField field = i.next();
            Expression fieldExpression = builder.getField(field).equal(builder.getParameter(field));
            if (directKeyExp == null){
                directKeyExp = fieldExpression;
            } else {
                directKeyExp = directKeyExp.and(fieldExpression);
            }
         }
        Expression expression = null;
        SQLDeleteStatement statement = new SQLDeleteStatement();

        // Construct an expression to delete from the relation table.
        for (int index = 0; index < getReferenceKeyFields().size(); index++) {
            DatabaseField referenceKey = getReferenceKeyFields().get(index);
            DatabaseField sourceKey = getSourceKeyFields().get(index);

            Expression subExp1 = builder.getField(referenceKey);
            Expression subExp2 = builder.getParameter(sourceKey);
            Expression subExpression = subExp1.equal(subExp2);

            expression = subExpression.and(expression);
        }
        expression = expression.and(directKeyExp);
        statement.setWhereClause(expression);
        statement.setTable(getReferenceTable());
        getDeleteQuery().setSQLStatement(statement);
    }

    /**
     * Initialize insert query. This query is used to insert the collection of objects into the
     * reference table.
     */
    @Override
    protected void initializeInsertQuery(AbstractSession session) {
        super.initializeInsertQuery(session);
        getContainerPolicy().addFieldsForMapKey(getInsertQuery().getModifyRow());
    }

    @Override
    protected void initializeSelectionStatement(AbstractSession session) {
        if (this.selectionQuery.isReadAllQuery()){
            ((ReadAllQuery)this.selectionQuery).addAdditionalField(getDirectField().clone());
        } else {
            SQLSelectStatement statement = (SQLSelectStatement)this.selectionQuery.getSQLStatement();
            statement.addTable(getReferenceTable());
            statement.addField(getDirectField().clone());
            getContainerPolicy().addAdditionalFieldsToQuery(this.selectionQuery, getAdditionalFieldsBaseExpression(this.selectionQuery));
            statement.normalize(session, null);
        }
        if (this.selectionQuery.isDirectReadQuery()){
            ((DirectReadQuery)this.selectionQuery).setResultType(DataReadQuery.MAP);
        }
    }

    /**
     * INTERNAL:
     * Iterate on the attribute value.
     * The value holder has already been processed.
     * PERF: Avoid iteration if not required.
     */
    @Override
    public void iterateOnRealAttributeValue(DescriptorIterator iterator, Object realAttributeValue) {
        super.iterateOnRealAttributeValue(iterator, realAttributeValue);
        ContainerPolicy cp = getContainerPolicy();
        if (realAttributeValue != null && !iterator.shouldIterateOnPrimitives()) {
            for (Object iter = cp.iteratorFor(realAttributeValue); cp.hasNext(iter);) {
                Object wrappedObject = cp.nextEntry(iter, iterator.getSession());
                cp.iterateOnMapKey(iterator, wrappedObject);
            }
        }
    }

    /**
     * INTERNAL:
     * Iterate on the specified element.
     */
    @Override
    public void iterateOnElement(DescriptorIterator iterator, Object element) {
        super.iterateOnElement(iterator, element);
        ContainerPolicy cp = getContainerPolicy();
        for (Object iter = cp.iteratorFor(element); cp.hasNext(iter);) {
            Object wrappedObject = cp.nextEntry(iter, iterator.getSession());
            cp.iterateOnMapKey(iterator, wrappedObject);
        }
    }

    /**
     * INTERNAL:
     * Related mapping should implement this method to return true.
     */
    @Override
    public boolean isDirectMapMapping() {
        return true;
    }

    /**
     * INTERNAL:
     * Merge changes from the source to the target object.
     * Because this is a collection mapping, values are added to or removed from the
     * collection based on the changeset.
     */
    @Override
    public void mergeChangesIntoObject(Object target, ChangeRecord changeRecord, Object source, MergeManager mergeManager, AbstractSession targetSession) {
        if (this.descriptor.getCachePolicy().isProtectedIsolation()&& !this.isCacheable && !targetSession.isProtectedSession()){
            setAttributeValueInObject(target, this.indirectionPolicy.buildIndirectObject(new ValueHolder(null)));
            return;
        }
        Map valueOfTarget = null;
        AbstractSession session = mergeManager.getSession();

        //collect the changes into a vector
        HashMap addObjects = ((DirectMapChangeRecord)changeRecord).getAddObjects();
        HashMap removeObjects = ((DirectMapChangeRecord)changeRecord).getRemoveObjects();

        //Check to see if the target has an instantiated collection
        if ((isAttributeValueInstantiated(target)) && (!changeRecord.getOwner().isNew())) {
            valueOfTarget = (Map)getRealCollectionAttributeValueFromObject(target, session);
        } else {
            //if not create an instance of the map
            valueOfTarget = (Map)containerPolicy.containerInstance(addObjects.size());
        }

        if (!isAttributeValueInstantiated(target)) {
            if (mergeManager.shouldMergeChangesIntoDistributedCache()) {
                return;
            }

            Object valueOfSource = getRealCollectionAttributeValueFromObject(source, session);
            for (Object iterator = containerPolicy.iteratorFor(valueOfSource);
                     containerPolicy.hasNext(iterator);) {
                Map.Entry entry = (Map.Entry)containerPolicy.nextEntry(iterator, session);
                containerPolicy.addInto(entry.getKey(), entry.getValue(), valueOfTarget, session);
            }
        } else {
            Object synchronizationTarget = valueOfTarget;
            // For indirect containers the delegate must be synchronized on,
            // not the wrapper as the clone synchs on the delegate, see bug#5685287.
            if (valueOfTarget instanceof IndirectCollection) {
                synchronizationTarget = ((IndirectCollection)valueOfTarget).getDelegateObject();
            }
            synchronized (synchronizationTarget) {
                // Next iterate over the changes and add them to the container
                for (Iterator i = removeObjects.keySet().iterator(); i.hasNext();) {
                    Object keyToRemove = i.next();
                    containerPolicy.removeFrom(keyToRemove, null, valueOfTarget, session);
                }

                for (Iterator i = addObjects.keySet().iterator(); i.hasNext();) {
                    Object keyToAdd = i.next();
                    Object nextItem = addObjects.get(keyToAdd);
                    if (mergeManager.shouldMergeChangesIntoDistributedCache()) {
                        //bug#4458089 and 4454532- check if collection contains new item before adding during merge into distributed cache
                        if (!containerPolicy.contains(nextItem, valueOfTarget, session)) {
                            containerPolicy.addInto(keyToAdd, nextItem, valueOfTarget, session);
                        }
                    } else {
                        containerPolicy.addInto(keyToAdd, nextItem, valueOfTarget, session);
                    }
                }
            }
        }
        setRealAttributeValueInObject(target, valueOfTarget);
    }

    /**
     * INTERNAL:
     * Merge changes from the source to the target object.
     */
    @Override
    public void mergeIntoObject(Object target, boolean isTargetUnInitialized, Object source, MergeManager mergeManager, AbstractSession targetSession) {
        if (this.descriptor.getCachePolicy().isProtectedIsolation()&& !this.isCacheable && !targetSession.isProtectedSession()){
            setAttributeValueInObject(target, this.indirectionPolicy.buildIndirectObject(new ValueHolder(null)));
            return;
        }
        if (isTargetUnInitialized) {
            // This will happen if the target object was removed from the cache before the commit was attempted
            if (mergeManager.shouldMergeWorkingCopyIntoOriginal() && (!isAttributeValueInstantiated(source))) {
                setAttributeValueInObject(target, getIndirectionPolicy().getOriginalIndirectionObject(getAttributeValueFromObject(source), targetSession));
                return;
            }
        }
        if (!shouldMergeCascadeReference(mergeManager)) {
            // This is only going to happen on mergeClone, and we should not attempt to merge the reference
            return;
        }
        if (mergeManager.shouldRefreshRemoteObject() && usesIndirection()) {
            mergeRemoteValueHolder(target, source, mergeManager);
            return;
        }
        if (mergeManager.isForRefresh()) {
            if (!isAttributeValueInstantiated(target)) {
                // This will occur when the clone's value has not been instantiated yet and we do not need
                // the refresh that attribute
                return;
            }
        } else if (!isAttributeValueInstantiated(source)) {
            // I am merging from a clone into an original.  No need to do merge if the attribute was never
            // modified
            return;
        }

        Map valueOfSource = (Map)getRealCollectionAttributeValueFromObject(source, mergeManager.getSession());

        // trigger instantiation of target attribute
        Object valueOfTarget = getRealCollectionAttributeValueFromObject(target, mergeManager.getSession());
        Object newContainer = containerPolicy.containerInstance(containerPolicy.sizeFor(valueOfSource));

        boolean fireChangeEvents = false;
        if ((this.getDescriptor().getObjectChangePolicy().isObjectChangeTrackingPolicy()) && (target instanceof ChangeTracker) && (((ChangeTracker)target)._persistence_getPropertyChangeListener() != null)) {
            fireChangeEvents = true;
            //Collections may not be indirect list or may have been replaced with user collection.
            Object iterator = containerPolicy.iteratorFor(valueOfTarget);
            while (containerPolicy.hasNext(iterator)) {
                Map.Entry entry = (Map.Entry)containerPolicy.nextEntry(iterator, mergeManager.getSession());
                ((ObjectChangeListener)((ChangeTracker)target)._persistence_getPropertyChangeListener()).internalPropertyChange(new MapChangeEvent(target, getAttributeName(), valueOfTarget, entry.getKey(), entry.getValue(), CollectionChangeEvent.REMOVE, false));// make the remove change event fire.
            }
            if (newContainer instanceof ChangeTracker) {
                ((ChangeTracker)newContainer)._persistence_setPropertyChangeListener(((ChangeTracker)target)._persistence_getPropertyChangeListener());
            }
            if (valueOfTarget instanceof ChangeTracker) {
                ((ChangeTracker)valueOfTarget)._persistence_setPropertyChangeListener(null);//remove listener
            }
        }
        valueOfTarget = newContainer;

        for (Object sourceValuesIterator = containerPolicy.iteratorFor(valueOfSource);
                 containerPolicy.hasNext(sourceValuesIterator);) {
            Map.Entry entry = (Map.Entry)containerPolicy.nextEntry(sourceValuesIterator, mergeManager.getSession());
            if (fireChangeEvents) {
                //Collections may not be indirect list or may have been replaced with user collection.
                ((ObjectChangeListener)((ChangeTracker)target)._persistence_getPropertyChangeListener()).internalPropertyChange(new MapChangeEvent(target, getAttributeName(), valueOfTarget, entry.getKey(), entry.getValue(), CollectionChangeEvent.ADD, false));// make the add change event fire.
            }
            containerPolicy.addInto(entry.getKey(), entry.getValue(), valueOfTarget, mergeManager.getSession());
        }
        if (fireChangeEvents && (getDescriptor().getObjectChangePolicy().isAttributeChangeTrackingPolicy())) {
            // check that there were changes, if not then remove the record.
            ObjectChangeSet changeSet = ((AttributeChangeListener)((ChangeTracker)target)._persistence_getPropertyChangeListener()).getObjectChangeSet();
            if (changeSet != null) {
                DirectMapChangeRecord changeRecord = (DirectMapChangeRecord)changeSet.getChangesForAttributeNamed(getAttributeName());
                if (changeRecord != null) {
                    if (!changeRecord.isDeferred()) {
                        if (!changeRecord.hasChanges()) {
                            changeSet.removeChange(getAttributeName());
                        }
                    } else {
                        // Must reset the latest collection.
                        changeRecord.setLatestCollection(valueOfTarget);
                    }
                }
            }
        }

        // Must re-set variable to allow for set method to re-morph changes if the collection is not being stored directly.
        setRealAttributeValueInObject(target, valueOfTarget);
    }

    /**
     * INTERNAL:
     * Perform the commit event.
     * This is used in the uow to delay data modifications.
     * This is mostly dealt with in the superclass.  Private Owned deletes require extra functionality
     */
    @Override
    public void performDataModificationEvent(Object[] event, AbstractSession session) throws DatabaseException, DescriptorException {
        super.performDataModificationEvent(event, session);
        if (event[0] == Delete && containerPolicy.shouldIncludeKeyInDeleteEvent()) {
            session.deleteObject(event[3]);
        }
    }

    /**
     * INTERNAL:
     * Overridden by mappings that require additional processing of the change record after the record has been calculated.
     */
    @Override
    public void postCalculateChanges(org.eclipse.persistence.sessions.changesets.ChangeRecord changeRecord, UnitOfWorkImpl uow) {
        // no need for private owned check.  This code is only registered for private owned mappings.
        // targets are added to and/or removed to/from the source.
        DirectMapChangeRecord mapChangeRecord = (DirectMapChangeRecord)changeRecord;

        Iterator it = mapChangeRecord.getRemoveObjects().entrySet().iterator();
        while(it.hasNext()) {
            Map.Entry<Object, Object> entry = (Map.Entry<Object, Object>)it.next();
            containerPolicy.postCalculateChanges(entry.getKey(), entry.getValue(), referenceDescriptor, this, uow);
        }
    }


    /**
     * INTERNAL:
     * Insert the private owned object.
     */
    @Override
    public void postInsert(WriteObjectQuery query) throws DatabaseException {
        Object objects;
        AbstractRecord databaseRow = new DatabaseRecord();

        if (isReadOnly()) {
            return;
        }

        objects = getRealCollectionAttributeValueFromObject(query.getObject(), query.getSession());
        if (this.containerPolicy.isEmpty(objects)) {
            return;
        }

        prepareTranslationRow(query.getTranslationRow(), query.getObject(), query.getDescriptor(), query.getSession());
        // Extract primary key and value from the source.
        for (int index = 0; index < getReferenceKeyFields().size(); index++) {
            DatabaseField referenceKey = getReferenceKeyFields().get(index);
            DatabaseField sourceKey = getSourceKeyFields().get(index);
            Object sourceKeyValue = query.getTranslationRow().get(sourceKey);
            databaseRow.put(referenceKey, sourceKeyValue);
        }

        // Extract target field and its value. Construct insert statement and execute it
        Object keyIter = this.containerPolicy.iteratorFor(objects);
        while (this.containerPolicy.hasNext(keyIter)) {
            Map.Entry entry = (Map.Entry)this.containerPolicy.nextEntry(keyIter, query.getSession());
            Object value = getFieldValue(entry.getValue(), query.getSession());
            databaseRow.put(getDirectField(), value);

            ContainerPolicy.copyMapDataToRow(getContainerPolicy().getKeyMappingDataForWriteQuery(entry, query.getSession()), databaseRow);
            // In the uow data queries are cached until the end of the commit.
            if (query.shouldCascadeOnlyDependentParts()) {
                // Hey I might actually want to use an inner class here... ok array for now.
                Object[] event = new Object[3];
                event[0] = Insert;
                event[1] = getInsertQuery();
                event[2] = databaseRow.clone();
                query.getSession().getCommitManager().addDataModificationEvent(this, event);
            } else {
                query.getSession().executeQuery(getInsertQuery(), databaseRow);
            }
            getContainerPolicy().propogatePostInsert(query, entry);
        }
    }

    /**
     * INTERNAL:
     * Update private owned part.
     */
    @Override
    protected void postUpdateWithChangeSet(WriteObjectQuery writeQuery) throws DatabaseException {
        ObjectChangeSet changeSet = writeQuery.getObjectChangeSet();
        DirectMapChangeRecord changeRecord = (DirectMapChangeRecord)changeSet.getChangesForAttributeNamed(this.getAttributeName());
        if (changeRecord == null) {
            return;
        }
        for (int index = 0; index < getReferenceKeyFields().size(); index++) {
            DatabaseField referenceKey = getReferenceKeyFields().get(index);
            DatabaseField sourceKey = getSourceKeyFields().get(index);
            Object sourceKeyValue = writeQuery.getTranslationRow().get(sourceKey);
            writeQuery.getTranslationRow().put(referenceKey, sourceKeyValue);
        }
        for (Iterator iterator = changeRecord.getRemoveObjects().entrySet().iterator();
                 iterator.hasNext();) {
            Object entry = iterator.next();
            AbstractRecord thisRow = writeQuery.getTranslationRow().clone();
            ContainerPolicy.copyMapDataToRow(containerPolicy.getKeyMappingDataForWriteQuery(entry, writeQuery.getSession()), thisRow);
            // Hey I might actually want to use an inner class here... ok array for now.
            Object[] event = null;
            if (containerPolicy.shouldIncludeKeyInDeleteEvent()){
                event = new Object[4];
                event[3] = containerPolicy.keyFromEntry(entry);
            } else {
                event = new Object[3];
            }
            event[0] = Delete;
            event[1] = getDeleteQuery();
            event[2] = thisRow;
            writeQuery.getSession().getCommitManager().addDataModificationEvent(this, event);
        }
        for (Iterator iterator = changeRecord.getAddObjects().entrySet().iterator();
                 iterator.hasNext();) {
            Map.Entry entry = (Map.Entry)iterator.next();
            AbstractRecord thisRow = writeQuery.getTranslationRow().clone();
            Object value = changeRecord.getAddObjects().get(entry.getKey());
            value = getFieldValue(value, writeQuery.getSession());
            ContainerPolicy.copyMapDataToRow(this.containerPolicy.getKeyMappingDataForWriteQuery(entry, writeQuery.getSession()), thisRow);
            thisRow.add(getDirectField(), value);
            // Hey I might actually want to use an inner class here... ok array for now.
            Object[] event = new Object[3];
            event[0] = Insert;
            event[1] = getInsertQuery();
            event[2] = thisRow;
            writeQuery.getSession().getCommitManager().addDataModificationEvent(this, event);
        }
    }

    /**
     * INTERNAL:
     * Propagate the preDelete event through the container policy if necessary
     */
    @Override
    public void preDelete(DeleteObjectQuery query) throws DatabaseException {
        if (getContainerPolicy().propagatesEventsToCollection()){
            Object queryObject = query.getObject();
            Object values = getAttributeValueFromObject(queryObject);
            Object iterator = containerPolicy.iteratorFor(values);
            while (containerPolicy.hasNext(iterator)){
                Object wrappedObject = containerPolicy.nextEntry(iterator, query.getSession());
                containerPolicy.propogatePreDelete(query, wrappedObject);
            }
        }
        super.preDelete(query);
    }

    /**
     * INTERNAL:
     * Rebuild select query.
     */
    @Override
    protected void initOrRebuildSelectQuery() {
        this.selectionQuery = containerPolicy.buildSelectionQueryForDirectCollectionMapping();
    }

    /**
     * INTERNAL:
     * Overridden by mappings that require additional processing of the change record after the record has been calculated.
     */
    @Override
    public void recordPrivateOwnedRemovals(Object object, UnitOfWorkImpl uow) {
        // no need for private owned check.  This code is only registered for private owned mappings.
        // targets are added to and/or removed to/from the source.
        Iterator it = (Iterator) containerPolicy.iteratorFor(getRealAttributeValueFromObject(object, uow));
        while (it.hasNext()) {
            Object clone = it.next();
            containerPolicy.recordPrivateOwnedRemovals(clone, referenceDescriptor, uow);
        }
    }

    /**
     * INTERNAL:
     * Remove a value and its change set from the collection change record.  This is used by
     * attribute change tracking.
     */
    protected void removeFromCollectionChangeRecord(Object newKey, Object newValue, ObjectChangeSet objectChangeSet, UnitOfWorkImpl uow) throws DescriptorException {
        DirectMapChangeRecord collectionChangeRecord = (DirectMapChangeRecord)objectChangeSet.getChangesForAttributeNamed(this.getAttributeName());
        if (collectionChangeRecord == null) {
            collectionChangeRecord = new DirectMapChangeRecord(objectChangeSet);
            collectionChangeRecord.setAttribute(getAttributeName());
            collectionChangeRecord.setMapping(this);
            objectChangeSet.addChange(collectionChangeRecord);
        }
        collectionChangeRecord.addRemoveChange(newKey, newValue);
    }

    /**
     * INTERNAL:
     */
    public void setDirectKeyField(DatabaseField keyField) {
        getMappedKeyMapContainerPolicy().setKeyField(keyField, descriptor);
    }

    /**
     * ADVANCED:
     * Set the class type of the field value.
     * This can be used if field value differs from the object value,
     * has specific typing requirements such as usage of java.sql.Blob or NChar.
     * This must be called after the field name has been set.
     */
    public void setDirectKeyFieldClassification(Class fieldType) {
        getDirectKeyField().setType(fieldType);
    }

    /**
     * ADVANCED:
     * Set the class type name of the field value.
     * This can be used if field value differs from the object value,
     * has specific typing requirements such as usage of java.sql.Blob or NChar.
     * This must be called after the direct key field has been set.
     */
    public void setDirectKeyFieldClassificationName(String fieldTypeName) {
        getDirectKeyField().setTypeName(fieldTypeName);
    }

    /**
     * PUBLIC:
     * Set the direct key field name in the reference table.
     * This is the field that the primitive data value of the Map key is stored in.
     */
    public void setDirectKeyFieldName(String fieldName) {
        setDirectKeyField(new DatabaseField(fieldName));
    }

    /**
     * INTERNAL:
     * Either create a new change record or update the change record with the new value.
     * This is used by attribute change tracking.
     */
    @Override
    public void updateChangeRecord(Object clone, Object newValue, Object oldValue, ObjectChangeSet objectChangeSet, UnitOfWorkImpl uow) throws DescriptorException {
        DirectMapChangeRecord collectionChangeRecord = (DirectMapChangeRecord)objectChangeSet.getChangesForAttributeNamed(this.getAttributeName());
        if (collectionChangeRecord == null) {
            collectionChangeRecord = new DirectMapChangeRecord(objectChangeSet);
            collectionChangeRecord.setAttribute(getAttributeName());
            collectionChangeRecord.setMapping(this);
            objectChangeSet.addChange(collectionChangeRecord);
        }
        if (collectionChangeRecord.getOriginalCollection() == null) {
            collectionChangeRecord.recreateOriginalCollection(oldValue, uow);
        }
        collectionChangeRecord.setLatestCollection(newValue);
        collectionChangeRecord.setIsDeferred(true);

        objectChangeSet.deferredDetectionRequiredOn(getAttributeName());
    }

    /**
     * INTERNAL:
     * Add or removes a new value and its change set to the collection change record based on the event passed in.  This is used by
     * attribute change tracking.
     */
    @Override
    public void updateCollectionChangeRecord(CollectionChangeEvent event, ObjectChangeSet changeSet, UnitOfWorkImpl uow) {
        if (event != null ) {
            //Letting the mapping create and add the ChangeSet to the ChangeRecord rather
            // than the policy, since the policy doesn't know how to handle DirectCollectionChangeRecord.
            // if ordering is to be supported in the future, check how the method in CollectionMapping is implemented
            Object key = null;
            if (event.getClass().equals(ClassConstants.MapChangeEvent_Class)){
                key = ((MapChangeEvent)event).getKey();
            }

            if (event.getChangeType() == CollectionChangeEvent.ADD) {
                addToCollectionChangeRecord(key, event.getNewValue(), changeSet, uow);
            } else if (event.getChangeType() == CollectionChangeEvent.REMOVE) {
                removeFromCollectionChangeRecord(key, event.getNewValue(), changeSet, uow);
            } else {
                throw ValidationException.wrongCollectionChangeEventType(event.getChangeType());
            }
        }
    }

    /**
     * PUBLIC:
     * Configure the mapping to use an instance of the specified container class
     * to hold the target objects.
     * <p>The default container class is java.util.Hashtable.
     * <p>The container class must implements (directly or indirectly) the Map interface.
     * <p>Note: Do not use both useMapClass(Class concreteClass), useTransparentMap().  The last use of one of the two methods will override the previous one.
     */
    @Override
    public void useMapClass(Class concreteClass) {
        if (!Helper.classImplementsInterface(concreteClass, ClassConstants.Map_Class)) {
            throw DescriptorException.illegalContainerClass(concreteClass);
        }
        containerPolicy.setContainerClass(concreteClass);
    }

    /**
     * PUBLIC:
     * Configure the mapping to use an instance of the specified container class
     * to hold the target objects.
     * <p>The container class must implement (directly or indirectly) the Map interface.
     * <p>Note: Do not use both useMapClass(Class concreteClass), useTransparentMap().  The last use of one of the two methods will override the previous one.
     */
    public void useTransparentMap() {
        setIndirectionPolicy(new TransparentIndirectionPolicy());
        useMapClass(ClassConstants.IndirectMap_Class);
    }

    /**
     * PUBLIC:
     * This is a helper method to set the key converter to a TypeConversionConverter.
     * This ensures that the key value from the database is converted to the correct
     * Java type.  The converter can also be set directly.
     * Note that setting the converter to another converter will overwrite this setting.
     */
    public void setKeyClass(Class keyClass) {
        TypeConversionConverter converter = new TypeConversionConverter(this);
        converter.setObjectClass(keyClass);
        setKeyConverter(converter);
    }

    /**
     * PUBLIC:
     * This is a helper method to get the object class from the key converter
     * if it is a TypeConversionConverter.
     * This returns null if not using a TypeConversionConverter key converter.
     */
    public Class getKeyClass() {
        if ((getKeyConverter() == null) || !(getKeyConverter() instanceof TypeConversionConverter)) {
            return null;
        }
        return ((TypeConversionConverter)getKeyConverter()).getObjectClass();
    }

    /**
     * PUBLIC:
     * This is a helper method to set the value converter to a TypeConversionConverter.
     * This ensures that the value from the database is converted to the correct
     * Java type.  The converter can also be set directly.
     * Note that setting the converter to another converter will overwrite this setting.
     */
    public void setValueClass(Class valueClass) {
        TypeConversionConverter converter = new TypeConversionConverter(this);
        converter.setObjectClass(valueClass);
        setValueConverter(converter);
    }

    /**
     * ADVANCED:
     * This method is used to have an object add to a collection once the changeSet is applied
     * The referenceKey parameter should only be used for direct Maps.
     */
    @Override
    public void simpleAddToCollectionChangeRecord(Object referenceKey, Object objectToAdd, ObjectChangeSet changeSet, AbstractSession session) {
        DirectMapChangeRecord collectionChangeRecord = (DirectMapChangeRecord)changeSet.getChangesForAttributeNamed(getAttributeName());
        if (collectionChangeRecord == null) {
            collectionChangeRecord = new DirectMapChangeRecord(changeSet);
            collectionChangeRecord.setAttribute(getAttributeName());
            collectionChangeRecord.setMapping(this);
            collectionChangeRecord.getAddObjects().put(referenceKey, objectToAdd);
            changeSet.addChange(collectionChangeRecord);
        } else {
            if (collectionChangeRecord.getRemoveObjects().containsKey(referenceKey)) {
                collectionChangeRecord.getRemoveObjects().remove(referenceKey);
            } else {
                collectionChangeRecord.getAddObjects().put(referenceKey, objectToAdd);
            }
        }
    }

    /**
     * ADVANCED:
     * This method is used to have an object removed from a collection once the changeSet is applied
     * The referenceKey parameter should only be used for direct Maps.
     */
    @Override
    public void simpleRemoveFromCollectionChangeRecord(Object referenceKey, Object objectToRemove, ObjectChangeSet changeSet, AbstractSession session) {
        DirectMapChangeRecord collectionChangeRecord = (DirectMapChangeRecord)changeSet.getChangesForAttributeNamed(getAttributeName());
        if (collectionChangeRecord == null) {
            collectionChangeRecord = new DirectMapChangeRecord(changeSet);
            collectionChangeRecord.setAttribute(getAttributeName());
            collectionChangeRecord.setMapping(this);
            collectionChangeRecord.getRemoveObjects().put(referenceKey, objectToRemove);
            changeSet.addChange(collectionChangeRecord);
        } else {
            if (collectionChangeRecord.getAddObjects().containsKey(referenceKey)) {
                collectionChangeRecord.getAddObjects().remove(referenceKey);
            } else {
                collectionChangeRecord.getRemoveObjects().put(referenceKey, objectToRemove);
            }
        }
    }

    /**
     * PUBLIC:
     * This is a helper method to get the object class from the value converter
     * if it is a TypeConversionConverter.
     * This returns null if not using a TypeConversionConverter value converter.
     */
    public Class getValueClass() {
        if (!(getValueConverter() instanceof TypeConversionConverter)) {
            return null;
        }
        return ((TypeConversionConverter)getValueConverter()).getObjectClass();
    }

    /**
     * INTERNAL:
     * Prepare and execute the batch query and store the
     * results for each source object in a map keyed by the
     * mappings source keys of the source objects.
     */
    @Override
    protected void executeBatchQuery(DatabaseQuery query, CacheKey parentCacheKey, Map referenceDataByKey, AbstractSession session, AbstractRecord translationRow) {
        // Execute query and index resulting object sets by key.
        List<AbstractRecord> rows = (List)session.executeQuery(query, translationRow);
        MappedKeyMapContainerPolicy mapContainerPolicy = getMappedKeyMapContainerPolicy();
        for (AbstractRecord referenceRow : rows) {
            Object referenceKey = null;
            if (query.isObjectBuildingQuery()){
                referenceKey = mapContainerPolicy.buildKey(referenceRow, (ObjectBuildingQuery)query, parentCacheKey, session, true);
            } else {
                referenceKey = mapContainerPolicy.buildKey(referenceRow, null, parentCacheKey, session, true);
            }
            Object referenceValue = referenceRow.get(this.directField);
            Object eachCacheKey = extractKeyFromTargetRow(referenceRow, session);

            Object container = referenceDataByKey.get(eachCacheKey);
            if ((container == null) || (container == Helper.NULL_VALUE)) {
                container = this.containerPolicy.containerInstance();
                referenceDataByKey.put(eachCacheKey, container);
            }

            // Allow for value conversion.
            if (this.valueConverter != null) {
                referenceValue = this.valueConverter.convertDataValueToObjectValue(referenceValue, query.getSession());
            }

            this.containerPolicy.addInto(referenceKey, referenceValue, container, query.getSession());
        }
    }

    /**
     * INTERNAL:
     * Return the value of the field from the row or a value holder on the query to obtain the object.
     */
    @Override
    protected Object valueFromRowInternalWithJoin(AbstractRecord row, JoinedAttributeManager joinManager, ObjectBuildingQuery sourceQuery, CacheKey parentCacheKey, AbstractSession executionSession, boolean isTargetProtected) throws DatabaseException {

        ContainerPolicy policy = getContainerPolicy();
        Object value = policy.containerInstance();
        ObjectBuilder objectBuilder = getDescriptor().getObjectBuilder();
        // Extract the primary key of the source object, to filter only the joined rows for that object.
        Object sourceKey = objectBuilder.extractPrimaryKeyFromRow(row, executionSession);
        // If the query was using joining, all of the result rows by primary key will have been computed.
        List<AbstractRecord> rows = joinManager.getDataResultsByPrimaryKey().get(sourceKey);
        // If no 1-m rows were fetch joined, then get the value normally,
        // this can occur with pagination where the last row may not be complete.
        if (rows == null) {
            return valueFromRowInternal(row, joinManager, sourceQuery, executionSession);
        }
        // A set of direct values must be maintained to avoid duplicates from multiple 1-m joins.
        Set directValues = new HashSet();

        Converter valueConverter = getValueConverter();
        // For each rows, extract the target row and build the target object and add to the collection.
        int size = rows.size();
        for (int index = 0; index < size; index++) {
            AbstractRecord sourceRow = rows.get(index);
            AbstractRecord targetRow = sourceRow;
            // The field for many objects may be in the row,
            // so build the subpartion of the row through the computed values in the query,
            // this also helps the field indexing match.
            targetRow = trimRowForJoin(targetRow, joinManager, executionSession);
            // Partial object queries must select the primary key of the source and related objects.
            // If the target joined rows in null (outerjoin) means an empty collection.
            Object directKey = this.containerPolicy.buildKeyFromJoinedRow(targetRow, joinManager, sourceQuery, parentCacheKey, executionSession, isTargetProtected);
            if (directKey == null) {
                // A null direct value means an empty collection returned as nulls from an outerjoin.
                return getIndirectionPolicy().valueFromRow(value);
            }
            // Only build/add the target object once, skip duplicates from multiple 1-m joins.
            if (!directValues.contains(directKey)) {
                directValues.add(directKey);
                Object directValue = targetRow.get(this.directField);
                // Allow for value conversion.
                if (valueConverter != null) {
                    directValue = valueConverter.convertDataValueToObjectValue(directValue, executionSession);
                }
                policy.addInto(directKey, directValue, value, executionSession);
            }
        }
        return getIndirectionPolicy().valueFromRow(value);
    }
}